Why does someone get fixated on something?

my dad used to tell the same (loonnnggg) stories (from long ago) - - 10 times in a row. and it could be "word for word"

I pictured his brain like a broken record. running thru to a point, then skipping back to the beginning.

my mom doesn't tell long stories about her past. she is different than how my dad used to be.

shes more in the present moment...and complains or fixates on certain problems she thinks are happening.

again I think of her brain malfunctioning(it is, with alzheimers) playing the recorded message in her thoughts and then skipping back to re-play.

Your profile says you are caring for your husband at home.

Does he have dementia?
That's often a reason for a "fixation".
It is so frustrating but is part of the disease.

My mother would tell me 50 times a day (I counted) that she had "itching powder" in her clothes. It's been going on for 4 years (the amount of times a day varies) but always daily. You want to pull your hair out as you scream at the top of your lungs!

Unfortunately, sometimes no amount of distraction veers them away from whatever they're fixated about. In one ear and out the other is the best policy unless they are pestering you. Then I would take a break in another room or get out of the house (with another person watching your hubby).

This is probably the most frustrating thing I've ever had to deal with. I sympathize with you.

Heave, we need more detail before we can attempt to give you an answer. Who are you writing about?