Any line NOT assigned to AA 2, 3, or 4 will be answered by AA-1.
Use line assignement (option 6) in AA2 to assign the lines to it. Remember to use the 3-digit line numbers (801, 802, 803, etc.)
The above assumes that the lines are assigned directly to the voice mail calling group.
If the lines hit the Auto Attendant via a different route, such as assigned to a different calling group that overflows to the voice mail calling group, or to an extension as Principal User, which covers to voice mail, you're going to need to find those assignments, then delete and re-create the associated mailbox, steering the calls to AA2 instead.
Start by looking at Extensions > More > Group Calling > 770 (or whatever you dial to reach voice mail) > Enter > Lines and Trunks > Inspect