How do I get my oscilloscope to read voltage correctly?

I bought a cheap Hantek 6022BE to learn with and I'm just trying to measure some voltage to check if it's accurate. I'm using openhantek6022 https://github.com/OpenHantek/OpenHantek6022 and also hscope on android. I'm measuring a 19v laptop power supply with the 10x setting on the probe and also a set of leads with a 20x attenuator. When I measure the power supply with my dmm I'm getting 19.22V with the scope I'm getting much higher or lower depending on where I set the voltage per division. Both programs have a calibration function which I did.

20x attenuator showing 19.6v

10x probe showing 20v

10x probe with 2v per division setting only showing 9.81V

Hscope showing 19.9v