First of all, you want "font". Second of all, don't do that.

Or "fount" from older, non-American English.

Fount is definitely more correct. If we're talking a baptismal font, then it's font, but if were talking a fount of knowledge, the correct term is fount with font sometimes being used but derived from fount.

Etymology 1, meaning 3: https://en.wiktionary.org/wiki/fount

Etymology 3: https://en.wiktionary.org/wiki/font

Thank you, I couldn’t remember which but I figured I’d hit Muphry’s Law either way.

Don't do what, exactly?

Do not mix more than 1.00mL of chlorine with more than 0.00mL of bleach.

Don't do what?

Return VHS tapes without rewinding.