By default, a new measure will have the same time and key signature as those of the song or of the measure before it. However, in some cases you may want to set different values to these signatures. If you don't know how to get this yet, just folow the steps below:

1. Select the measure by selecting any note of it (the measure needs to have at least one note).

2. Select button "---" on the toolbar, and choose "Edit Selected Measure" on the popup menu.

3. Choose the time or key signature you wish to set, then press "Done".

Demo video:

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