1990 Buick Riviera sterio

Hello, which fuse is it? There are usually two circuits. Does the fuse blow before or after you turn on the key and radio.

If you unplug the feed from the radio and the fuse still blows, looks like a short on that circuit, between the fuse and radio.

its the second fuse at first the back speakers would go out then come back on when they wanted to, then after a few months it blew the fuse to the radio so i put a new one in and it lasted about 30 minutes and blew again so i put another one but 20 amp instead and it started to smoke and the fuse started to melt so i took it out and now the electrical light blinks on my dash!! how do i unplug the feed to the radio ?

Unplug the connector from the radio. Don't use a higher rated fuse.