Are your files binary files set to writable? Assuming you’re using P4V you can right click on the binaries, choose ‘change filetype’ and select the ‘w’ option to allow them to be writable rather than the standard perforce behaviour of making files read only.
Note that this does not automatically check out the files if a change does happen, so you might need to do that part manually when you’re ready to commit.
Another option is not to track the binaries in Perforce, you might not need them in there but depends on how you work with your team and your build process.
If you do need to track your binaries, you could also set how many versions are tracked within perforce in order to save space. You don’t really need to have all the versions as the binaries are easily built from code. You can set this from the ‘Change Filetype’ menu too.