How do I see which quests have I completed?

Pushing the L key displays the active quests. When I complete them, they disappear from the Log. Is there a way to see the quests that I have already completed?

Nope. Once it's gone, there's no way to tell if it's been done or not.

Its something I always hoped they would fix in an update.

You'd basically have to go to a Wiki, write down the list of quests, and check them off as you go. And, you'd have to check now and then for added quests.

Yea it does suck, no idea why they dont add this

you can check and restart eye of the north quests afetr u get the hero book in gunnar's hold, but other than that there is no way.

I can certainly understand how this could be frustrating. Other than knowing if you can team up w/ someone to complete some quest you may or may not have done, why would you need to know if you've done a quest? Is it to check if you've met some prerequisite?

A good idea would be to have a system of little keepsakes noted on your journal that basically signify completing a specific quest - something like "piece of fabric you kept for delivering the blankets to the Ascalonian settlers" or somesuch...

I would love to know which quests i have done, it is a shame there wasnt a way to tell

Well, I'm pretty sure it's obvious, but you can talk to the NPC you're supposed to get a quest from.