Jimmy,
Only the "D" seat armrests on the 19s and 20s release. You have to slide your hand on the inside side of the armrest back between the inside armrest and the side of the seat back cushion to feel for a little button. Depress the button at the same time lift the armrest.
It's a little tricky to find but makes it a lot easier for elderly and customers with disabilities to get into the seat row.
Laura