Re: Changing clefs, time and / or key signatures

[Mats Bengtsson]

To expand Han-Wen's answer a bit: Just insert the 
\clef, \time or \key command within the music wherever
you want it to happen. 

The Gallina piece by Merula supplied in the distribution
examplifies time signature changes and some other 
features specific to baroque music.

   /Mats B