2/4 in need to written in 4/4!

If this means you want to make all of the 1/4 notes 1/2 notes and all of the other notes twice as long as well, then as long as there are no time changes or key changes, you can select all (press ctrl+a) then paste right where it is now (or to an empty score) using the menu Edit->Paste Double Duration and everything will be twice as long. Note that tempo changes, rehearsal marks and other system items will be in the wrong place, that's why I suggested an empty score. In the case of key changes, after you past to an empty score, all you'll need to do is enter the key signature.

In the case of any internal time signature changes (which seems unlikely) you will need to break the score in pieces and paste each time signature section with the new time signature in place before you paste.