Sharing and permissions, custom access, cant get user to have read and write acess

Hello everyone, i have a Netgear Stora NAS on my MAC, its located in the finder under shared, when i click on it i sign in with my user account and it gives me my folders to my stora, on one of my folder (Movies), i clicked get info and under sharing and permissions it told me i had custom access, i changed the privelages of the name,"Everyone" from no access, to read and write, when i did this, the name on tope of this (the main username) vanished. so ive been searhing on how to get my privelages back, i went to + and added new GROUP "admins" and it gave me my main username back but now with read only acess, when i try to change it to read and write it dissapears, PLEASE HELPPPPP, thank you!!!!

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