I always get “mad” (we don’t actually get upset with each other) at a friend of mine because he uses the UK versions
for the past tense of verbs like *spill* or *spell*, saying *spilt* or
*spelt* instead of the American versions like *spilled* or *spelled*, etc. He’s “retaliated” (just teasing) by saying ✻*feeled* and ✻*builded* rather than *felt*
and *built*.

Does anyone know why American English changed *‑t* to *‑ed* only for certain
verbs but not for others?