I've been told solfege will help me play a melody by ear and have been learning about it.
One thing that really confuses me, is do I approach it by using intervals to remake the song? For example when hearing a melody, should I hear it go to a minor 3rd up, then a major 3rd up, and so on and so on? Or should I internalize scale degrees and what each one sounds like, for example when I hear notes, I'd know that's the 4th scale degree to 5th scale degree etc?
Also, would I use fixed, or movable do to achieve this?