i've got a question. say i'm playing a I-IV-V progression with my left hand, starting with an E chord, and tapping a melody according to the E major scale with my right hand. would i keep tapping notes that belong to the E major scale when i switch to the IV or V chord, or would i tap notes that belong to the scale of whatever the IV or V chord is? thanks!
it would be conventional to keep within the E major scale. You may however want to emphasise the notes of the chords you play (maybe focus your melody more around the C# for the A chord for example)

Of course there is nothing stopping you tapping notes from the scale of the IV or V scale (or indeed any notes), but you would still be in the key of E major (unless you made a key change, but you don't want to do that every chord) so would still conventionally use the notes from the E major scale.
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