The rule: newest goes first

TikTok fills your profile from the top-left. Your newest post, your newest pin and your newest repost always take that first spot and push everything else one place to the right.

So a banner has to be built backwards. The piece you want on the far left goes up last. Post the left piece first instead, and it ends up on the right: the banner reads backwards.

Posting order for a three-piece banner. The 1st tile is the right piece.

Posting order

  1. Post the 1st tile, the right piece, as a photo post.
  2. Post the 2nd tile, the middle piece.
  3. Post the 3rd tile, the left piece.

Post the three back to back. If another video goes up in between, it lands inside the banner and splits it.

Pinning order

You can pin up to three posts on TikTok, and pinned posts sit at the start of your profile ahead of everything else. The most recently pinned post appears first.

That means pinning follows the same rule as posting: pin the 1st tile, then the 2nd, then the 3rd. If older videos are already pinned, unpin them before you start, since the limit is three.

Pinned right to left, the banner holds the top row even after you post new videos.

Pinning decides the order of the top row on its own. If you posted the pieces out of order, pinning them right to left still gives you a correct banner.

Repost banner order

A repost banner lives in your Reposts tab instead of your main grid. That tab also shows the newest repost first, so the order is the same: repost the right piece first, then the middle, then the left.

TikTok's Repost button is for other people's posts, so the pieces have to be posted by another account first: a second account of yours, a friend, or a banner account that shares pieces for reposting. The repost banner maker previews your Reposts tab and lists the steps.

Fix a banner that shows up wrong

What you seeWhyFix
Banner reads backwardsPinned or reposted left to rightUnpin all three (or remove the reposts) and redo them right to left
Two pieces swappedPinned out of orderUnpin those two and pin them again in order
Banner moved down a spotA new post or repost went in front of itPin the banner, or remove the newer repost
Top and bottom trimmed9:16 pieces in a 3:4 gridSplit again with 3:4 tiles

Questions

Does posting order matter if I pin the banner?
Less, because the pin order sets the top row. It still matters for anyone scrolling your posts before you pin, so posting right to left is a good habit.
How do I change the order of pinned posts?
TikTok has no drag-to-reorder for pins. Unpin the posts and pin them again in the order you want, newest pin first.
Why does my banner look right to me but wrong to others?
Check that you are looking at the same tab. A pinned banner shows on your posts grid; a repost banner shows only in the Reposts tab.
Which piece is the 1st one?
The right piece. In RepostGrid's files it is the one whose name ends in post-01-of-03-right, and the tile preview labels it 1st.