When you create a new project, by default it has one time signature that lasts for the entire project.
When Show Advanced Tools is selected in the Advanced preferences pane, you can add time signature changes to a project in the Signature List, Signature track, or Score Editor.
Do one of the following:
Click the Add Signature button 
in the Signature List, then edit the values in the Time Signature dialog.
In the Score Editor, drag the time signature symbol from the Part box to the target time position.
Click the target time position in the Signature track with the Pencil tool, then edit the values in the Time Signature dialog.
You can enter beat groups for composite time signatures in the Beat Grouping field. The total number of beats in the bar is calculated by the sum in this field. For example, entering the numbers 223, becomes “2+2+3.” The sum is displayed as the numerator unless the Print Composite Signature checkbox is selected. Beat Grouping affects the way in which notes are beamed together (in both cases).
You can also change the automatic beaming in normal time signatures. In 4/4-time “1+1+1+1” produces four beamed groups (one for every beat), instead of the two groups displayed as a default.
Select the Hide Signature checkbox to hide a time signature change in the score printout. The signature is still displayed onscreen, but is crossed out, and won’t be included in the calculation of spacing between notes and symbols. As a result, signatures may overlap notes on the screen, but not in the printout. This can be used for notating cadenza-like passages, which contain more notes than would normally fit the time signature.