When reading voltage, you may notice the voltage reading is fluctuating drastically or incorrect when on a known voltage source, this is usually a sign of an internal fuse being blown. Test fuse with a continuity meter, and replace the fuse recommended by the owners manual.
When a fuse is blown on the ammeter setting, the reading won’t have any fluctuation when in the series circuit being measured. Again, test fuse with a continuity meter, and replace the fuse recommended by the owners manual.
If replacing the fuse does not fix the issue, you may want to look into a new Multimeter, click here.