Navigate to the Dial Plan menu
Select User Term and hit [+] then ENTER.
Type "I" for "Insert.
Select the module and slot from the drop-down menu.
What Jay said is correct.
In the ATLAS, the only configuration that sets the "role" for an interface is under the DIAL PLAN, and then you set what the ADTRAN is terminating to. So in "Network Term" the ADTRAN is terminating to the network (Telco), an in "User Term" the ADTRAN is terminating to user equipment.
That said, in the NETWORK TERM the ADTRAN is in the "user" role connecting to the network, and in the USER TERM the ADTRAN is in the "network" role connecting to user equipment.
Hope this helps,