Sponge PEX v2.0 default group issue

I am having an issue, i have used multiple different commands to set default users when people log in. When people log in they are not set to the default group i do not know why. I have used /pex group default def false and that screwed up alot so i had to completely redo PEX on my server, now it is running good but i do not want to mess it up again with that command. I know there is a way to set every player that logs in to the default group automatically so i do not have to do each player as they log in. Please someone give me a hand. Thanks

Do
/pex default user parent add group <groupname>

All new users will then be in the specified group.

Thank you i have done this, last issye i am running into is how do i allow players to use pixelmon npc shops that are placed in an admin claim from griefprevention plugin for sponge 1.8.9?

Thank you i have done this, last issye i am running into is how do i allow players to use pixelmon npc shops that are placed in an admin claim from griefprevention plugin for sponge 1.8.9?