You can access the items in collections using a For/EndFor loop.
This example moves all the forms in a ChildForms collection to the left by 5 pixels:
For Each(#Current) In(#ChildForms)
Change Field(#NEW_LEFT) To('#Current.Left - 5')
Set Com(#Current) Left(#New_Left)
Endfor
This example disables all the items in submenu #smnu_1:
For Each(#Current) In(#smnu_1.Items)
Set Com(#Current) Enabled(False)
Endfor