Question:

I want 3 users to be able to edit picklists without having any other administrative access. I gave them access to the tools-->manage-->picklists menu item but any changes they make can only be seen by themselves and not other users.

Ive come across something like this before and did a sql update to make the modifyuser of the picklist item ADMIN which makes it visible to all users but its not feasible to do this every single time these 3 users edit a picklist.

Have i missed something in the permission process?

Answer:

You need to grant them access to SLX Administrator and assign an "administrative role" to them. 
Uncheck all rights except "PickList Manager".

(plus install SLX Admin on their workstation)