Help changing a melody line in treble clef to bass clef--any shortcuts?

I am attempting to change a melody line that is in treble clef to the same melody in bass clef for a string bass to play. I thought there was a shortcut to this, but I cannot find it. This is existing music, not my original creation. The music is available in musescore. I was hoping to just transpose it, but it only goes down about an octave and it remains in treble clef. My bassist only reads bass clef. Thanks in advance for any help you can provide.