sourcetree osx diff program issues

[Eric LW]

I can't update my external diff program, I downloaded DiffMerge but when I go into sourcetree preferences > diff, it just has filemerge greyed out, I can't change anything and I can't use Diff Merge conveniently. Help?

[KieranA]

Hi Eric,

This is most likely because you've got the "Allow SourceTree to modify your global Mercurial and Git configuration files" option disabled in the "General" tab of the SourceTree preferences as shown here:

If this is disabled you can't modify your diff prefs because you won't be able to modify your global configuration. Enabling this option will allow you to change your preferences.

Hope that helps