Since the dawn of time,
my phone app will not clear it out even when I exit and clear it out a few times, I have to jump back and forth, otherwise the name of my person will still remain there after I tend to clean it, it takes me around ten times to clean out a simple phone call..... So really frustrating.
when you say clearing out, what do you mean? clearing cache for the phone app? or the device itself? clearing out data? or just rebooting the phone?
Hmmmmm, you might want to think about trying a factory reset. You should not have to do a clean like that that often. Maybe starting from a clean slate is what the phone needs.

Make sure you backup accordingly.