Hi, Guys! Do you know how can I tigten the friction of Osmo phone mount in this direction?

https://drive.google.com/open?id=0B6S0qaDpHfwAU1FsVm5Wd3ZPSFk

Thank you for your assistance,  I tried to tighten this screw but it does not affect the friction in this direction. Maybe there is some inside screws that can adjust tension? I tried to mount ipad mini, but it rotate all the unit because of low friction