Cinematic Mode Video -- Locking onto subject?

Hello,

When shooting Cinematic Video on my iPhone 15 Pro I am having some trouble figuring out how to film/edit in an efficient manner.

Especially in a busy environment like at a concert, the phone will identify the band on stage, but also all of the tons of heads in front of me, for example.

The iPhone will then automatically try to switch the focus around which I do not want.

After I record the video, if I go to edit it to change the focus points, I see there are sometimes 10-30 white dots on the "film strip" where the phone is automatically switching the focus points.

When I double tap on my subject to enable AF tracking lock, this works for some time but then the phone will jump again later in the video to another subject. This appears to be quite random and happens even when there is a grey box around the person/subject II originally locked on to.

Does anyone have any tips on how to deal with all of these white focus dots / focus shifting?

I realize you can tap and hold to lock focus distance, but if there are better tips for how to lock the subject better that would be helpful