Hi yophie, from inside MoI if you go to Options > General > "Edit .ini file" button, that will bring up a window that shows the path to the moi.ini file.

By default on Mac it is stored under ~/Library/Application Support/Moi/moi.ini

A couple of things to note, the ~ is short for your user folder, /Users/<your user name>/

By default the Library folder is hidden, you can go there in the Mac finder by going to the "Go" menu on the top menu bar and pick the "Go to folder" menu item then put in ~/Library/Application Support/Moi

Or also you can show it by pushing Shift+Cmd+.(period) , that will show hidden directories for the rest of that finder session.

Let me know if you still have any trouble locating it.

- Michael