The Iceland international was deployed as a central midfielder by interim boss Duncan Ferguson earlier this season.
And Sigurdsson admits he was surprised about new manager Carlo Ancelotti continuing to use him in an unfamiliar role.
"I didn't know if he was joking," Sigurdsson told the club's website.
"There are a lot of things I have to think about in games I've never thought about before; if we are attacking I have to sit back and make sure we are set up defensively if we lose the ball.
"The things I love are scoring goals and getting in the box, getting on the end of crosses and taking up positions where the ball might fall to you.
"It has always been my target to attack and score goals.
"It took a couple of games to get used to something different but I have started to enjoy that position.
"If it had happened five or six years ago, I wouldn't have been too happy.
"But as you mature and gain more experience it is a good challenge to play a new position and think about completely different things.
"Carlo is a very experienced and successful manager and we have a good relationship.
"It is nice to be in his team and if you are playing, you are happy."
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