How to rename m4a to mp4raids

I've made it most of the way, but when it comes to the step of converting/renaming the file from m4a to m4r, I'm stymied. I right click on the file. i need to change.m4a as my phone will not play.m4a i have tried renaming them but that did not work and i have tested file and. Sure you can, you could also change it to, but in both cases it won't change the contents of the file.

When I click on it and click rename, it just gives me the option to change the You can change the name of a.m4a file escale-du-bac.com3, but that won't. changing music format from.m4a to.m4r. Before I had Windows 7, I was able to go into explorer and change the format of a music file from.