You're right, it doesn't let you have anything other than 10 in the bell value text field! This is a bug that slipped by me. I'll fix it ASAP. Until it's fixed, here's a link to version 1.7 which works as advertised, but without some of the newer features of v1.8.: http://members.ozemail.com.au/~ronfleckner/metronome/met17.zip

If you don't care about having a bell accent on anything above beat 10, then you can still use the newer 1.8 version. You can check if the bug has been fixed and the fixed version available via the app's Check For Update... menu item

Ron