problem with electrical system

Also let me state and this might be important. The battery was hooked up wrong. I was assuming yes I know the old saying. That the RV 12 volt system was like a car and the black wire was neg and the yellow wire must have been pos. but I knew something was wrong when my bathroom and microwave fans were not blowing through the vents they were trying to pull. That's when I had an epiphany that they were running in reverse and the battery was hooked up backwards. That's when I moved the black wires to pos. and the yellow to neg on the battery posts. Now the fans run correctly but the fuses keep blowing. I bought this RV used about 7 years ago and only used it 4 times during ythat time period and forget sometimes how everything works.