How do I change first computer to another name

Hello. This is first post and hopefully I can find an answer. I recently purchased an HP All in One computer for my husband. When setting it up, I put it in my name (my name shows up when the computer turns on). I also registered Microsoft in my name. I loved his computer so much, I purchased one for myself. Again, I put my name in/on it. However, now I want his name to appear when he turns on his computer but I don't know what I need to change. Also, when we were fiddling with his computer, I noticed that things I had searched for in Edge, was appearing on his computer. That's definitely weird. Can someone tell me how to change his computer? Thanks.

Thank you for such a prompt response. Does making his account an administrator account change mine from being an administrator account? Or will both be PCs be independent of each other? Thanks again.

Thanks - I turned syncing off. Tomorrow I will tackle setting his account up on his computer. Thanks for all your help.