I have a very interesting problem now, when I move the throttle, sometimes the motors don't slow down when I bring it back down, and will speed up each time I move it up again, for example if I were to full throttle, then bring the stick all the way back down, the motors might act as though they were at half throttle...?

It does this while flying with the props on?

If you try to use the radio throttle with the props off it will do strange things like this. That is normal because the props are not on.

If you are testing the motors with props off on the bench then that behaviour is normal. Have a watch of the following video to understand why...

Ok okay, thanks! I flew it for the first time, and flew it a few times... absolutely amazing. Definitely glad I chose 6s. Thanks for all your help!