It sounds like you're in the Customer Access Panel rather than the Control Panel (cPanel, LPCP, or possibly some other control panel, depending on operating system and age of the server). Once you're in the control panel, you'll see somewhere on its front page some sort of "File Manager". There may also be a "Legacy File Manager" there (just a different flavor of FM). I know there's a way to change permissions in cPanel's File Manager(s), and presumably it's similar for LPCP. You navigate to the directory or file you want to change permissions on. You click on the name of the directory or file, and a bunch of options come up somewhere over on the right side of the screen. Click on something mentioning "permissions" and you should get something that allows you to update the permissions. Note that in at least the cPanel Legacy FM, you had to tick/untick the 9 boxes -- you couldn't simply overwrite the three digit number.