Set up correct php configuration on ubuntu server to solve prestashop backend issue graphics

Hello, i recently migrate my server to a virtual server, i have installed ubuntu 20 and prestashop 1.7.4 at the moment everything is fine expect some section of backend , for example product and other things, somebody told me the issue could be cause from php version, now i have instaled 7.4.24, and i get suggestion to try with 7.2,
7.2 is allready installed but when i set on primary php version nothing works anymore looks apache also not working anymore.
I need to fix these things, and let prestashop works perfectly.