Your mind has a week off with this easy one. It’s simple: Across doesn’t end with a “t”.
Keep your ears open. Lots of people add the letter “t” to across and it comes out sounding like ‘acrossed.”
Perhaps the “t” has been added because many of us say something like “We went across to the whatever….” We slide right from the “s” of across and right into the “t” of to.
That’s cool. But let’s leave the “t” with to when we don’t follow across with that word.
My apologies—you might start hearing “acrossed” all over the place now. I hope you don’t.