Fretboard playback

Hi There: First Off... awesome program!
I'm sure the following challenge is just my lack of understanding of the Musescore features... i'm a new newbie, so please excuse my ignorance.

I have a bar with a chord designation of Eb. I've created a guitar fretboard diagram (barre at 6th fret, etc.) which has a "C" chord designator above it. I've selected the option not to show the "C", so it looks great when printed out, outstanding. But when I play the piece, both the C and Eb play. So can I turn off the C chord, or change it to Eb on the fretboard symbol and remove the Eb chord designator?

Have searched the handbook, but nothing found as yet.

Thanks for any help.

Cheers, Bruce from Boulder