As a senior, Andersen was named first-team All-State at quarterback and safety, as well as the Montana Defensive Player of the Year, after he passed for 1,403 yards, rushed for 877 yards, and scored 30 total touchdowns on offense and had 71 tackles with three interceptions and two fumbles recovered on defense while Beaverhead won the Class A state championship.

[4] He moved to quarterback before his sophomore season after two-year starter Chris Murray was ruled academically ineligible to play.

He was named first-team all-conference after finishing the season with 54 tackles, 11.5 for loss, and 6.5 sacks with one interception and five passes broken up.

[8] As a redshirt senior, Andersen was named the Big Sky Defensive Player of the Year and was the runner-up for the Buck Buchanan Award.

[18] His father played college basketball at Eastern Oregon University, while his sister ran track at Montana State.