It's useful to spend some time on individual tones/intervals and how they interact with chords. Some intervals, like this one, have a rather special function.
In this lesson (an excerpt from my Chord Connections course), we look specifically at the 4th (long name, perfect fourth) over major chords.
The 4th is typically considered a "passing tone" over major (e.g. a major triad or maj7). It functions as a passing bridge between the 3rd and 5th chord tones, since holding it over major creates dissonance because of how it clashes with the 3rd. Yet it can be used very effectively in creating melodic lines.
Training your eyes and ears to the functionality of this interval will help you to use it more consciously and musically...
