@mitu Hi, that's great info thanks. I presume that if it isn't writable, then pastern.com will allow me to change it?
The weird thing is that it was working so well, and then for no reason it stopped. Also, it is allowing me to do the first edit (ie try another emulator) and seems to write it to the config file, but then won't let me further edit it. Its the same in every emulator - PS1, SNES etc. Got me confused!
Will try what you suggest tho. Thanks again, appreciate it.