midi gets input even if Musescore is not being used

In my best John Cleese voice, I wish to register a complaint. I know everyone will say it is my own fault, but help me avoid this in the future. It has happened several times already. If Musescore is open, and I am using another program like Logic Pro, any notes I play on a synthesizer get entered into Musescore. This creates an unredeemable mess. Since I almost always enter notes with a cursor in Musescore, isn't there a way I can set the default to NOT have MIDI entry? I found I can set the MIDI device to none, but is this global, that is work on all projects? I really think Musescore should automatically be set to not enter notes unless it is the frontmost program.