The British heavyweight has faced calls to part ways with long-time coach Rob McCracken since losing his WBA (Super), WBO and IBF titles to Usyk last month.
Joshua has met Virgil Hunter, Eddy Reynoso and Ronnie Shields in the US.
"I guess he didn't feel it was the right [gameplan against Usyk] so he wanted to make a change," said Shields.
Hunter is based in Oakland, California and trained the likes of multiple-weight world champion Andre Ward and Amir Khan.
Joshua has close ties within Hunter's camp with British fighter Joshua Buatsi also training under the veteran coach.
Reynoso is famous for guiding boxing superstar Canelo Alvarez to the top of the sport and the 44-year-old also trains WBC super featherweight champion Oscar Valdez and Joshua's former opponent Andy Ruiz Jr.
Shields, who is based in Texas, confirmed rumours Joshua was on the hunt for a new trainer after welcoming him into his gym this week.
Jermall Charlo works under Shields and posted several videos on his Instagram of Joshua speaking with his coach and doing some light training.
Joshua has not made a final decision on his coaching staff, which also includes assistant trainers Angel Hernandez and Joby Clayton.
After his defeat by Ruiz Jr, Joshua added Hernandez to his team and the 32-year-old could yet stay with McCracken as his head coach.
A switch to the US would see Joshua have to move his training headquarters away from Sheffield where he has spent his entire professional and amateur career.
McCracken has trained Joshua since his amateur days, but was heavily criticised for the gameplan against Usyk.
Joshua was completely outclassed by Usyk and convincingly beaten after deciding to try and outbox the former undisputed cruiserweight champion.