OK, I downloaded a new version of Start10 from the link suggested by The_Gear, having logged in to my account, and saved it in my downloads. I then uninstalled Start10 and restarted the PC. I then re-installed from the new downloaed version and..........................the same thing happnes, no change - clicking Switch User from the Shut Down options from the left click menu of Start10 does absolutely nothing, zero, zilch.
Oh, and I temporarily disabled my anti-virus software whilst re-installing Start10.
So.........................where do I go from here, please?