Pianissimo Notation and Key Signature

[ConnollyMusicCreates]

I have a piano tune in C minor from back in the day. At the time I didn't know about setting up the key at the outset, so now when I look at the notation I have a stack of accidentals throughout instead of three flats at the beginning. I was trying to get the notation into C minor but couldn't figure it out.

Edit: How would I do that, assuming it's possible, without having to manually enter the pitches? Thanks

[ConnollyMusicCreates]

I have a pianist who would like the sheet music but I'm still trying to figure out how to add the key signature so the 3 flats will take care of themselves. The attachment shows (I think) the project is set up for C minor. Also, would I need to print it out and snail mail it or is there a way to attach it as a .pdf? Not quite seeing that as an option but I could be missing it. Thanks