Can't change the tracking speed - it is greyed out

I have a student who is unable to double tap quickly enough for it to register on the iPad. I see that I should be able to adjust the tracking speed in the Accessibility options, but I am unable to do so because that option is greyed out. Any suggestions for a fix? Thanks!

 

I can't find anything to support this, but I believe that Track Speed is a setting for the joystick mentioned. It probably won't go active without that device attached.

I tried creating a custom gesture for a double tap, but had no luck making it work.

Sorry not to be of more help.