is there a way to change the enhancement of a card after its already max level?
oh and also i wanted to ask if u could make it so that already bought items from the style shop would appear less since its kinda annoying to keep resetting just to get 3 new styles
Sadly, the answer to both of your questions is no.
There are no ways to change the enhancement/attribute of an Upgrade card, regardless of its level.
And there are no ways to prioritize un-bought (is that a word?) items into showing more. But this gave me an idea for a Boost item, though... But I can't make any promises.