You don't have to just use the chords in one key.

Use the chords in the keys next to them.

There is a common misunderstanding in music that when a song is written in a specific key, the chords in the song should all fit into that key. This is not always true. Always remember that music is a conglomeration of mathematics, patterns and formulas all brought together to make rhythms and melodies to please the ear. Sometimes you have to think outs…