Not sure exactly what you want to do, but to move button assignments around:
Moving line buttons
FEATURE *81
Change the position of your line or hunt group buttons.
1. Press FEATURE *81.
2. Press the line button that you want to move.
3. Press the button to which you want to move the line.
4. Press RLS. The two buttons are exchanged.
5. Update the button label strip on your telephone.
Line buttons cannot be exchanged with intercom, answer DN, or handsfree
buttons.
If the line presently is not assigned to your phone, you will need the programming password, not the admin, and need to program the lines. Depending on your KSU/software combo menus will vary, but you need to generally get into Configuration, then Line Access, put in the set number of your phone (DN), Select Line Assignment, then scroll through each line and either add or remove it from your set. This assumes you are dealing with a single line and not a hunt group. From there, you may need to your the Feature *81 to move the lines to the buttons you want.