Try this if neither of the previous ideas of this thread worked
In a terminal enter : xinput
you should get something looking like this :
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ ETPS/2 Elantech Touchpad id=14 [slave pointer (2)]
⎜ ↳ MOSART Semi. 2.4G Wireless Mouse id=10 [slave pointer (2)]
⎣ Virtual core keyboard id=3 [master keyboard (2)]
↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]
↳ Power Button id=6 [slave keyboard (3)]
↳ Video Bus id=7 [slave keyboard (3)]
↳ Video Bus id=8 [slave keyboard (3)]
↳ Sleep Button id=9 [slave keyboard (3)]
↳ USB Camera id=11 [slave keyboard (3)]
↳ Asus WMI hotkeys id=12 [slave keyboard (3)]
↳ AT Translated Set 2 keyboard id=13 [slave keyboard (3)]
Locate your touchpad, mine here is called is called "ETPS/2 Elantech Touchpad" (on the third line).
now, once you've done this enter : xinput --list-props "whatever your touchpad is called to print your device xinput properties
for instance mine would be nathan@linux-engine:~$ xinput --list-props "ETPS/2 Elantech Touchpad"
Device 'ETPS/2 Elantech Touchpad':
Device Enabled (135): 1
Coordinate Transformation Matrix (137): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000
Device Accel Profile (263): 1
Device Accel Constant Deceleration (264): 2.500000
Device Accel Adaptive Deceleration (265): 1.000000
Device Accel Velocity Scaling (266): 12.500000
Synaptics Edges (288): 123, 2974, 114, 2005
Synaptics Finger (289): 1, 1, 0
Synaptics Tap Time (290): 180
Synaptics Tap Move (291): 165
Synaptics Tap Durations (292): 180, 180, 100
Synaptics ClickPad (293): 1
Synaptics Middle Button Timeout (294): 0
Synaptics Two-Finger Pressure (295): 282
Synaptics Two-Finger Width (296): 7
Synaptics Scrolling Distance (297): 75, 75
Synaptics Edge Scrolling (298): 0, 0, 0
Synaptics Two-Finger Scrolling (299): 1, 1
Synaptics Move Speed (300): 1.000000, 1.750000, 0.053305, 0.000000
Synaptics Off (301): 0
Synaptics Locked Drags (302): 0
Synaptics Locked Drags Timeout (303): 5000
Synaptics Tap Action (304): 2, 3, 0, 0, 1, 3, 0
Synaptics Click Action (305): 1, 3, 0
Synaptics Circular Scrolling (306): 0
Synaptics Circular Scrolling Distance (307): 0.100000
Synaptics Circular Scrolling Trigger (308): 0
Synaptics Circular Pad (309): 0
Synaptics Palm Detection (310): 0
Synaptics Palm Dimensions (311): 10, 200
Synaptics Coasting Speed (312): 20.000000, 50.000000
Synaptics Pressure Motion (313): 30, 160
Synaptics Pressure Motion Factor (314): 1.000000, 1.000000
Synaptics Resolution Detect (315): 1
Synaptics Grab Event Device (316): 1
Synaptics Gestures (317): 1
Synaptics Capabilities (318): 1, 0, 0, 1, 1, 1, 1
Synaptics Pad Resolution (319): 32, 31
Synaptics Area (320): 0, 0, 0, 0
Synaptics Soft Button Areas (321): 1548, 0, 1737, 0, 0, 0, 0, 0
Synaptics Noise Cancellation (322): 18, 18
Device Product ID (255): 2, 14
Device Node (256): "/dev/input/event5"
Look carefully for "two fingers scrolling". for instance, mine is Synaptics Two finger scrolling (299). If the values in that line are something else than 1, 1, there, you have it!
fix it with : xinput --set-prop "touchpad name" "scrolling option" 1 1.
Once again, mine as an exampe : nathan@linux-engine:~$ xinput --set-prop "ETPS/2 Elantech Touchpad" "Synaptics Two-Finger Scrolling" 1 1.
Results should be immediate but temporary. Add the xinput command (the last one only) somewhere (presumably at end) of the file /home/<you>/.bashrc which is automatically run when you enter a session (or open a terminal).