C15 Score - detach DS, etc.. and make DS sign larger?

How do I attach the DS sign, rehearsal letter, DS al Coda, etc., to the bar line, or, free float them? What score does is stack them above the rehearsal letters, attached to the notes, (here, the rest on one) so I get this big gap between staves ----

AND - how do I make the DS sign larger, independent of other signs, fonts, etc.?