To properly fix permissions for all domains in a GoPanel account (including addon domains and subdomains)
$ /go/fix all

To properly fix permissions for one specific domain (gopanel.org) in your GoPanel account
$ /go/fix gopanel.org

If you have a specific temporary need for 777 permissions (for debugging only).
$ /go/fix gopanel.org 777

Here's the most secure and proper way to fix permissions for a single domain, with important security considerations
$ /go/fix gopanel.org 755
755 is Recommended Instead of 777

To set files and folder permissions to 555 (read and execute for owner, group, and others)
$ /go/fix gopanel.org 555