"Settings>Devices>Touchpad and Mouse>Advanced settings>Disable>Apply>OK"
Bit puzzled by this. When I go to Settings>Devices>Touchpad and Mouse
there is no Advanced settings.
I disabled the touchpad on my Toshiba Satellite Pro using the function button, which worked fine.
I also found that I could disable it at "Settings>Devices>Touchpad and Mouse>Additional Mouse Options/Device Settings
Then highlight Synaptics Touchpad and click Disable.
Both of these options work and are carried over between reboots. The advantage of using the function button, is that if for any reason the mouse fails, you can easily re-enable the touchpad.
Incidentally, there is no need to click Apply before clicking OK.
OK means "apply changes and close the window"
Apply means "apply changes and leave the window open"