Some people find this particular implementation of "search" to be a bit unintuitive.

When you search for anything, make sure you do so from a list of forum posts or forums. If you type in the search box with a *thread* open, it'll only search in that thread

The basic approach is to grab the quests with one character, share them one-by-one with everybody else and hit the AcceptAll macro, which is bound to the same key on all WoWs.

For quests that need an item, you're going to have to go to each instance of WoW and click the quest giver manually. The "picture in picture" feature of Keyclone makes this less painful than it would otherwise be when you're running multiple WoWs on a single machine, but you still need to get clicking!