Old dog new trick 

Saying you can or can't teach something to someone once they've gotten past the time when they learned their ideals/ways. Saying you can or can't change someones mind about their long term opinions or beliefs. can be referring to a human as well.

A: my dog won't listen when I tell him to sit!
B: yeah, you can't teach an old dog new tricks.

A: but can't you just hear me out on this, B?
B: no! I made up my mind a long time ago.
A: *sigh* you can't teach an old dog new tricks.

A: I'm 70 years old but I just learned rock climbing!
B: you can teach an old dog new tricks!

Old dog new trick by Rileyisafk December 18, 2022

you can't teach an old dog new tricks 

It means that it is very hard to change someones habits

You can't teach an old dog new tricks when they have been used to using a cell phone instead of a smart phone.

you can't teach an old dog new tricks by Zahraa June 13, 2017

teach an old dog new tricks 

when someone does something for a long time and its hard to teach them new abilities.

you cant teach an old dog new tricks, my uncle never learned how to use his cellphone.

teach an old dog new tricks by Andre the CRACKER DACKER November 18, 2016