Selecting material per face not working

So from what I read, this is what I try. In edit mode, change to face select mode. Select faces, and then select a new material in the material properties tab. It mentions I need to hit assign, but as soon as I change the material, the entire object changes to this material. I am using 3.4.1 what am I doing wrong?

Works fine for me in 3.4.1:

Thanks for the video, I see that I was changing the material the wrong way and was chaning using the “Browse Material to be Linked” drop down instead of the selection at the top.