using the tool with a curved monitor and another regular external monitor?

Hello: I am a new user of the Better Touch Tool, and have a question.

I have a Macbook Pro connected to a Samsung curved monitor, as well as a Dell regular display monitor. I have heard that the Better Touch Tool helps to ensure proper sizing when shifting between the curved monitor (which does not display correctly), and the regular (Dell) monitor (where it does). I keep the Macbook Pro closed when using these monitors, so I can't use the Touch Bar. I don't have a Track Pad, but just use a regular mouse. Can anyone help me?

thanks so much, SL