Volta
Volta brackets or first and second ending brackets are used to mark different endings for a repeat.

To place a volta bracket on the score drag-and-drop the item from the lines palette.
The brackets can span more than one measure. Double click the volta to enter edit mode and then move the handles with:
- one measure right Shift+Right
- one measure left Shift+Left
These commands move the "logical" start or end of the volta bracket which determines playback in MuseScore and layout over multiple systems. Moving the handles using the left or right arrows keys only or using the mouse allows finer adjustments but does not change how the repeat is played.
If you move the handles, a dashed line from the logical position to the actual position is shown

Text
You can change the text and many other properties of a volta bracket using the Line Properties dialog. Right-click on a volta bracket and choose Line Properties.... The figure below shows the volta text as "1.-5."


You can also right-click on the Volta and bring up the Volta Properties dialog. From here you can change both the displayed Volta text (the same from the Line Properties above) and the Repeat List. If you want one volta to be played only on certain repeats and another volta on other repeats, enter the repeat times in a comma separated list. In the example below, this volta will be played during repeat 1, 2, 4, 5 and 7. Another volta will have the other ending, like 3, 6 and possibly other higher numbers like 8, 9, etc.

Playback
Sometimes a repeat plays for more than two times. In the figure above the volta text indicates that it should play five times before it continues. If you want to change the number of times MuseScore plays a repeat then go to the measure containing the repeat bar line and change its Repeat Count (see Measure operations for details).
Issues with multi-part scores
In version 0.9.4 or earlier you can only place voltas on the top staff of a multi-part score. Otherwise you may encounter bugs such as the MuseScore crashing when you create parts (see bug report) or the anchor position moving when you reload the score.