Your PHP scripts will run under the account userid. Since your PHP scripts run under your userid, you must take this into consideration when you are trying to create, edit, or modify files with your PHP scripts.

Secondly, PHP scripts do not run under the group "nobody" as well. Therefore, in order to allow PHP to create, modify, and/or delete files within your account, you would need to have 755 permission on the files and within the directories where the files will be created not 777.