Batch Edit Artist Info

I’ve got 837 artists listed from either United States of America, United States, or USA. Is there any way to combine these to say, USA? If I select all, there’s no edit option.

Try to do it in 2 times, about 400 each. Most probably (based on experience of another user) edit option will appear.

Doesn’t work. If I select one, edit option is available. If I select two, it’s not.