If you unpack .ap files using 7zip, then the unpacked files will be 'Read-only'
There are two ways around this:-
1. Unpack your .ap files using RW_Tools from the Files/Find all .ap files menu - doing it this way will correctly unpack the .ap files into their correct folders and automatically make them Read/Write
2. Do as you have done, then in RW_Tools under the Options menu there is an option to make selected files Read/Write.