Welcome to Guitar Trick..
You just found the hard one for most everyone.
There are a few different ways to attack it.
Some like to start with your index on B & E..
strum and check if they sound clearly..
then add your middle finger on G, strum and see if they ring clear..
add your ring and try again.
go through this several time which build muscle memory.
You may have to fine tune your finger placement minutely..
It also gets easier as your finger tips get harder.
Some like to try it as a BAR Chord.. index fingering across the whole neck. then you may still have to roll or curl your index finger to get it to sound clearly..
I would work with both way. You will need both in your guitar venture.
It all a matter of practice.