That's pretty neat. I am usually heading up when i have 10 mins of NDL left.
I just checked mine. doesn't let me change it. I dive w 2 computers, and the other one is an old Tusa IQ700 and pretty sure that doesn't let me change it either. but I will add the 2 extra mins.
I just googled it when it got mentioned here, and looks like it's a debated topic.
If you're diving a wall or reef, just watch the fish at 5 meters as you are still diving. Watch your air and depth however.