Fisher said Monday that he was sticking with Davis, who made his NFL debut earlier this season after Hill was sidelined with an injury. Fisher had said Davis was the starting quarterback for the rest of the season.
The team confirmed the switch before practice Wednesday.
Hill began the season as the replacement for Sam Bradford, who was sidelined for the second straight year with a knee injury. However, Hill injured his thigh in the opener.
Davis had two interceptions and lost a fumble in the fourth quarter in Sunday's 31-14 loss at Arizona. The Rams had led 14-10 entering the quarter.
The Seattle Seahawks are placing tight end Zach Miller on injured reserve after he struggled in returning from ankle surgery.
Seattle Coach Pete Carroll said Wednesday that Miller will need a second surgery to get the problems in ankle corrected. Miller underwent surgery during Seattle's bye week after its Week 3 victory over Denver.
The hope was that Miller would only miss a few games, but his recovery went longer than planned. Carroll said Miller got to the point of running on the ground, but could never progress any further.
"He's pretty matter of fact about it. He doesn't feel right. He's not ready. It's not like he's close to getting back. It's been a long process," Carroll said. "He had a nasty ankle."
The New Orleans Saints placed receiver Joseph Morgan back on the active roster, ending his two-game suspension for an unspecified violation of team rules. ... San Chargers inside linebacker Manti Te'o returned to practice after missing six games with a broken right foot. Running back Ryan Mathews, out since spraining his right knee in a victory against Seattle on Sept. 14, is expected to play in Sunday's home game against Oakland. He returned to practice during the Chargers' bye week.