User with sudo access can not install software using GUI

Hello everyone

My machine is running: Almalinux 6.8.7-1.el9.elrepo.x86_64
and has a local user account (UserA).
Initially, userA could install software using the GUI but his admin privileges were removed. I was then asked to give him back admin privileges so I added him back to the sudoers file.
UserA can now install software using sudo on the terminal but not using the GUI. The GUI tells him that he does not have permissions to install software.

What do I need to do to make the GUI work for him again?

Many thanks