Usage patterns
大して〈形容詞〉ないnot very ~ (used to downplay a quality)
This movie wasn't all that interesting.
大して〈動詞〉ないnot do ~ very much / not ~ particularly
He doesn't study very much, yet he gets good grades.
大して変わらないnot much different; barely changes
The price hasn't changed much from last year.
大して気にしないnot care much (about something)
It's a small mistake, so I'm not too bothered about it.