Page numbers are rendered in PageSmallText. Making it bigger will also make the Copyright bigger:
!NoteWorthyComposer(2.751)
|PgSetup|PageNumbers:1
|Font|Style:PageSmallText|Size:16|CharSet:1
|RestMultiBar|NumBars:8
|Bar
|Boundary|Style:NewSystem|NewPage:Y
|RestMultiBar|NumBars:8
|Bar
|Boundary|Style:NewSystem|NewPage:Y
|RestMultiBar|NumBars:8
|Bar
|Boundary|Style:NewSystem|NewPage:Y
!NoteWorthyComposer-End
Or you can use MarkupPage.rg
Perhaps, like this:!NoteWorthyComposerClip(2.751,Single)
|User|MarkupPage.rg|Pos:0|Class:StaffSig|Opts:,3,,,,,,,,4,3|m1:/f6.5/p0|m2:/f6.5/p0
|RestMultiBar|NumBars:8|
|Bar
|Boundary|Style:NewSystem|NewPage:Y
|RestMultiBar|NumBars:8|
|Bar
|Boundary|Style:NewSystem|NewPage:Y
|RestMultiBar|NumBars:8|
|Bar
|Boundary|Style:NewSystem|NewPage:Y
!NoteWorthyComposerClip-End