you can do something like this: sudo apt-get install xserver-xorg-input-synaptic=0.15.2-0ubuntu8
If it doesn't work you can get the deb package and install it manually
Also, can you attach the output of this command again (after settings the values which work for you)? xinput list-props 7
replace 7 with the identifier of your synaptic device.
you can do something like this: xorg-input- synaptic= 0.15.2- 0ubuntu8
sudo apt-get install xserver-
If it doesn't work you can get the deb package and install it manually
Also, can you attach the output of this command again (after settings the values which work for you)?
xinput list-props 7
replace 7 with the identifier of your synaptic device.