it's always been a bit of a juggling act. sometimes it gets so screwed up, you just need to reset and start over. (edit > display order > reset default) Also, you can shift groups of 'stuff' in display order, so they shift up/down but keep their relationships.
Lastly, you can use the element info pallet (window > pallets > element info) to check each elements assigned display order number.
as a new feature request I've been throwing around for quite a few years, I'd LOVE to see an element display order manager. something we can select elements and manually assign their display order numbers or move them in a list... but that request has never been responded to yet... maybe I'll give it a bump on the wishlist forum
BIM solutions and trouble shooting (self proclaimed) expert. Using Archicad 26 5002 US on Mac OS 11.5.2
I element information does not give an accurate answer in this cross section. No matter how much you change, the value does not change. For example, if it is 7, it does not change even if you raise it, but only a warning message appears saying that the maximum value has been reached. Is it true that we have this bug?