One very interesting detail about the song's origin is that the tune for YESTERDAY came to Paul McCartney in a dream. He awoke, and after playing it on a piano, was convinced that he had stolen it from another song. However, after a few weeks, his fears resolved, he penned the lyrics. This also was the first use of other musicians (a string quartet) along with a Beatles recording.
You have probably been getting comfortable with a lot of Major chords, and a few Minor and Seventh (7th) chords by now. YESTERDAY, along with a few other songs we've been learning, introduces a Major 7th (Fma7) and a couple of Minor 7th chords. With a bit of explanation, they shouldn't be a major (or minor) problem for you.
Here are the "new" chords in YESTERDAY. You've probably seen some of these before, the Bm7 recently in "Sunshine on My Shoulders", in which we added another note in the
If you're NOT the analytical type-- then please just ignore the following. If you ARE the analytical type-- here, the Bm7 naturally moves into the E7 chord. The Bm7 here resembles an E7sus4 chord, the only difference being the BASS note (here, we used a "B" instead of playing the open "E" string). Oftentimes, just changing one note of a chord, sometimes the Bass note, changes the entire chord.
In the last two lines [the bridge] there are two instances of rapid chord changes, from Am--G--Fma7. Each chord is only played one beat or strum. This may be too difficult for you at this time. If it is, use a shortcut by playing an Am with a G bass (Am/G) instead of the full G chord. This can also be used on the first line of the song, when going from Am to Fma7.
NOTE: Sometimes chords are appended or changed, usually to accommodate an extra note. Often, this is the bass note. Sometimes it is a note on the higher end. You will see these chords designated in two ways. Either you will see a Plus (+) sign, as in C+9, or Cadd9, or you will see a chord with a Slash (/), as in this chord-- Am/G. The slash usually indicates an ALTERNATE BASS note. Normally, the Am chord is played with an "A" bass. A chord's bass note normally corresponds to the name of the chord. For example, C is normally played with a "C" bass note, D with a "D" bass note, G with a "G" bass note. But here a Slash (/), followed by an alternate note, indicates the use of a different bass note.
There are two ways to play the Am/G chord. Here are the chord diagrams for them.
The Am chord is shown on the Left, and the two versions of Am/G are shown on the RIght.
I prefer the chord diagram in the middle. It only involves THREE fingers, instead of FOUR. It does involve moving your 3rd (ring) finger from the 3rd string to the 6th (top) string. For me, that is NOT so difficult. It may be more difficult for you-- at first. The more you play and practice it, the easier and more comfortable it will become. Try both-- and I think you'll agree that the middle chord is easier too. The open strings sound better. And you will NOT have to use your pinky finger!