I’m not even able to find this ‘Preferences’ image (see above) any longer (showing General. AUR tab etc.) What has gone wrong? Do I need to re-install Manjaro … again? I’m finding Manjaro becoming more and more frustrating to the point I’m about to give up on it.
Pamac UI was updated in the last update. AUR option is still in the settings but maybe the window is a little different.
In the main Pamac window, click on the “hamburger” menu (the 3 lines) and select preferences. After you provide your credentials, a new window opens with some tabs. One of the tabs is “Third party”. There you can enable AUR.
You can also enable AUR editing the file /etc/pamac.conf. There, uncomment (remove the #) from the EnableAUR line.
PS: There is hardly any case where is necessary to reinstall the whole system. You have to mess up real bad the system for that. This applies probably for the majority of Linux distros.