MuseScore allows you to transpose the playback of a staff, without affecting the music notation. This simulates the effect of a capo (Wikipedia) on the instrument.
To add a capo:
- Add staff text to the note/rest from which you want capo playback to start;
- Right-click on the staff text, select Staff Text Properties..., then click on the Capo Settings tab;
- Check the "Capo Settings" checkbox, and set Capo fret to the fret number you wish to apply the capo at (each fret increases the pitch by a semitone);
- Click Ok to apply your changes;
- Edit the wording of the text as desired.
Capo playback will apply from the note that the staff text is attached to, until either the next staff text with "Capo Settings" enabled, or until the end of the score. A Capo fret setting of "No capo" will remove any capo previously set for a staff, returning it to its original tuning.