thanks, swapped the ini from my backup and back to working

You need to replace the parameters.ini file in your profile folder. For some reason this can get corrupted and causing this setting to always revert to next tool to use

Just want to say thanks. I just had this exact same issue happen to me. I found this thread, and tried first to just change the value in the controls panel, but every time I did it just reverted. So I found that my parameters.ini file was corrupt. Just removed that and let mach4 recreate it then all was good.