> I am using BuddyPress and tried your suggestion but it didn’t change anything
Did you do a buddypress profile name update after checking profile syncing?
Checking that won’t affect changes that have already been done.
If you don’t need to change it through the buddypress profile, the there’s that plugin Robin suggested, or you could change in the WordPress user fields.
If buddypress is essential to what you’re doing, there is also a buddypress forum:
https://buddypress.org/support/
And also these guys, who seem so provide more answers than the official forum (they have a “paid” category but they answer question even if you don’t pay):