Melted ground wire

"The 200 is for A/C power and 20 is for D/C power that’s why it jumps like that"

There are 2 - 200 v ranges one red and one black. the black 200 range should read the same as the black 20 range. The thing about ranges is measuring a small voltage on a higher voltage range results in a less accurate reading

Example...

(Just made up numbers for example only)

1.5v on the 2v range would read 1.523

1.5 on the 20v range might read 1.5v

1.5v on the 200 v range might read 2v