http://usermanuals.finalemusic.com/Finale2014Win/Content/Finale/Page_layout.htm

1. Choose the Page Layout tool . ...
2. Choose Page Layout > Space Systems Evenly. ...
3. Under Space Systems Evenly On, specify the desired page(s), or choose All Pages to include the entire document.
4. Select Place ___ Systems on Each Page and enter the number of systems you want to place on the selected pages.
5. Click OK.

Or...

Under the page layout menu, click on system 1, from the dropdown menu choose "Resize Page (Page Reduction)". You'll see the current reduction being used. Enter a smaller number and make sure "Page 1 through the end of the piece" is selected. Press OK.

Check your score to see if it's too big, too small or perfect. Repeat the steps above if needed. Once you have the correct size, respace music and update layout if needed.

Another option is to resize the staff systems. This option is also under the page layout menu.

You can also use the Resize Tool.

There is a convenient context menu in the Resize Tool.

NB: Remember to update the settings in {Page Format for Score} so that all new systems/pages get formatted to the same sizing.

Thanks! 3 friends. 

I try Mike method first, but not all staves inclusively, Peter and Jeffrey did, thanks again. 

best

Shing-kwei