My thank you page is showing as the 'original layout' and not as what I created

I have built a campaign starting with a Landing page, but no matter WHAT I do, the thank you page doesn’t show the way I built it. It does in the builder, but not in ANY test…

Please help me, I can;t go live until it works…

That can happen if you copied it initially from one that was already done from another campaign. Is that the case here?

Yes I did! So probably that happened, but why does it? Is that just a weird bug or is there logic to this?