community server default notification setting won't change to "mention only"

hey guys !

i just recently realised that there is an option for turning your server to a community server.

i did so and in the setup process i chose the notification default to be "@mentions only".
on all my channels (when i right click to check the notification type) it still says that the default is set to "all messages". i can't figure out how to change that. i don't want people to leave because of spam.

i will be greatful for any solutions to this problem.