Linux Mint XFCE.

Going into Mouse and Touchpad > Touchpad > Pointer Speed > Acceleration:

BUT changing the acceleration doesn't actually change acceleration, it adjusts speed.

Cinnamon and MATE have different sliders for speed and acceleration and actually worked.

*To clarify, there is only one slider. Yes I am selecting touchpad from the drop down box. The header says "Pointer Speed", the slider says "Acceleration" but adjusts speed. IIRC cinnamon has 2, one for speed and one for accleration, which is what you expect.