There seems to be a lot of that with yourself. However, as I have pointed out before, and do so here again, 'you' are not the standard by which to base things upon.
... you are influencing anyone to change their thinking about that.
I am simply sharing what I have been given by God, through the word (Bible) and the historical continuity associated to those things, and all are free to accept or reject those things, based upon the convictions that the Holy Ghost / Spirit brings upon them. I do not change anyone's heart, only God's words written there by the Spirit of the LORD can.
Since You identify as Seventh Day Adventist, ...
I do not merely "identify", I surely am a Seventh-day Adventist, even chosen by God's Holy Ghost / Spirit! I am part of that prophetically foretold "remnant" (Rev. 12:17), called the Seventh-day Adventist movement, which are the spiritual successors to these:
1Ch_12:32 And of the children of Issachar, which were men that had understanding of the times, to know what Israel ought to do; the heads of them were two hundred; and all their brethren were at their commandment.
1Ki 18:17 And it came to pass, when Ahab saw Elijah, that Ahab said unto him, Art thou he that troubleth Israel?
1Ki 18:18 And he answered, I have not troubled Israel; but thou, and thy father's house, in that ye have forsaken the commandments of the LORD, and thou hast followed Baalim.
Isa_40:3 The voice of him that crieth in the wilderness, Prepare ye the way of the LORD, make straight in the desert a highway for our God.
Mat 3:1 In those days came John the Baptist, preaching in the wilderness of Judaea,
Mat 3:2 And saying, Repent ye: for the kingdom of heaven is at hand.
Mat 3:3 For this is he that was spoken of by the prophet Esaias, saying, The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight.
Mar 1:1 The beginning of the gospel of Jesus Christ, the Son of God;
Mar 1:2 As it is written in the prophets, Behold, I send my messenger before thy face, which shall prepare thy way before thee.
Mar 1:3 The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight.
Mar 1:4 John did baptize in the wilderness, and preach the baptism of repentance for the remission of sins.
Luk 3:2 Annas and Caiaphas being the high priests, the word of God came unto John the son of Zacharias in the wilderness.
Luk 3:3 And he came into all the country about Jordan, preaching the baptism of repentance for the remission of sins;
Luk 3:4 As it is written in the book of the words of Esaias the prophet, saying, The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight.
Joh 1:19 And this is the record of John, when the Jews sent priests and Levites from Jerusalem to ask him, Who art thou?
Joh 1:20 And he confessed, and denied not; but confessed, I am not the Christ.
Joh 1:21 And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No.
Joh 1:22 Then said they unto him, Who art thou? that we may give an answer to them that sent us. What sayest thou of thyself?
Joh 1:23 He said, I am the voice of one crying in the wilderness, Make straight the way of the Lord, as said the prophet Esaias.
Son_3:6 Who is this that cometh out of the wilderness like pillars of smoke, perfumed with myrrh and frankincense, with all powders of the merchant?
Son_8:5 Who is this that cometh up from the wilderness, leaning upon her beloved? I raised thee up under the apple tree: there thy mother brought thee forth: there she brought thee forth that bare thee.
Rev 12:6 And the woman fled into the wilderness, where she hath a place prepared of God, that they should feed her there a thousand two hundred and threescore days.
Rev 12:14 And to the woman were given two wings of a great eagle, that she might fly into the wilderness, into her place, where she is nourished for a time, and times, and half a time, from the face of the serpent.
Rev 12:17 And the dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ.
... should I see this as where you learned these false and unsound doctrines?
I am actually an ex-Roman Catholic (30 years, and worked with the local Bishop here, and served in a specialized ministry thereof which EWTN stated were 'Expert in their field', and worked with family that also worked with specific Catholic ministries, such as the 'Right to Life' and 'Bishop Gallegos Maternity Home' here in CA), and had never even heard of a Seventh-day Adventist all that time. Yet, in very brief, after learning about Creation from a Baptist ministry, and the Historical evidences for the resurrection of Jesus from a Pentecostal scholar / professor, and reading in the many others, like Luther, Melanchthon, Wesley's, Calvin, D'Aubigne's Reformation History, Lord Acton's History on St. Bartholomwe's Day, and De Bethune's eyewitness of the same, Foxe's Martyrs' and parts of Acts & Monuments, Wylie's history, Benjamin G. Wilkinson's Truth Triumphant, and other such things while I had begun to actually read and study the scriptures (at first it was a St. Joseph's ed. NAB (still at the house, I think) with catholic Deutero-Canon (Apocrypha), and later to a King James Bible, things began to become more and more clear, as I read more and more in the Bible, church history (even including Philip Schaff's, &c.), and dove into the so-called 'ecf' (the easily confused fellows), and later into the mss (manuscripts) in koine Greek, Latin (Vetus Latina, Jerome's), Hebrew, and other languages (Italian (Diodati), French (Olivetan, Ostervald), German (Luther, &c.), Spanish (Reina-Valera), Genevan's and even Origen's Hexapla (Greek) and others still.
I became a Seventh-day Adventist in 2008 because of those things (and after reading the book, "Desire of Ages" and later "Great Controversy", then "Patriarchs and Prophets", "Prophets and Kings", "Acts of the Apostles", "Steps to Christ", "Ministry of Healing", and then served in their ministry, such as at Amazing Facts (2008-2017), and taught / preached in several churches.
That this is what they believe?
Pick anything I have said in my posts, and I will show you sister White herself saying essentially the same, as well as from the pioneers and writers / publishers of the church. However, when someone really wants to know what a Seventh-day believes and practices without middle 'men', simply pick up a King James Bible and start quoting, and thereafter will always be the "Amen" of the "remnant".