The surname Trollsås has different origins. There is one family in Sweden and another one in Norway. The families in Sweden and Norway are as far I know not related to each other.
The surname Trollsås in Sweden has its origin from the province of Jämtland in Sweden. My grandfather Per-Olof Olsson who lived in a small village, Trollsåsen, added the name Trollsås to his surname. After that it became the surname of the family.
Per-Olov Trollsås