Personalizing the default "take it" assignment to a user-specific group

Within our agency, our agents are split into a variety of groups with the ultimate goal of separating what each group can see from the others. By default, our "take it" button next to the Assignee field assigns it to the agent in our main group that everyone, all departments, is included in. Is there a way to a) customize the "take it" button so that each user will assign it to themselves within their own group or b) remove the "take it" option all together. We have set up macros, located at the bottom of the ticket module, so that when they select the take it option within the macro, it will assign the ticket to them within their proper group. Unfortunately, our users keep confusing the macro's action with the "take it" link located in a much more visible location next to the Assignee drop down menu.