ToME: the Tales of Maj'Eyal

I found a stronger version of an inscription that i have active, How do i swap them? I've googled this but only find guides about how useful different inscriptions are and not how to use or manage them. Also, should i just sell my gems or will i need them for anything, i'm a thalore archer? Thank you!

You have by default 3 inscription slots, 2 of which are probably already taken up (most likely by a wild infusion and a regeneration infusion.), and you can add a new inscription to one of your slots by 'u'sing the infusion/rune. If you already have all your slots full, using one will bring up a menu asking you which of your slots you want to overwrite. You cannot remove an inscription, but you can overwrite them as many times as you want. If you overwrite one, however, remember that it's gone forever, and you'll need to 'u'se a new inscription to overwrite again when you want to change.

Also, you can have up to two of the same type of infusion (note that artifact infusions are considered unique relative to their more common cousins), but if you try to add a third it will ask you to replace one of your first two even if you have an empty slot.

And also note that it's very dangerous to overwrite inscriptions during combat - a new inscription is always put on cooldown.