Assistive Touch is a floating icon on the screen, giving you quick access to some some system settings. To add and enable assistive touch on LG G5 (Touch Assistant), do as follows:
1. Open the Settings app on your G5
2. On the List view, scroll to the System settings and touch to open the Accessibility settings (On the Tab view, go to the General tab and find the Accessibility there)
3. Touch the Motor & Cognition settings, under the Type settings
4. Now tap to open the Touch Assistant settings, under the Motor settings
5. Make sure to enable the Assistive Touch toggle button on the top side of the screen
6. And then the floating icon should appear on the screen.