idiom
teach an old dog new tricks
intentar enseñar a alguien algo que es difícil de aprender debido a su edad o experiencia
Meaning
to try to teach someone something that is difficult for them to learn due to their age or experience
Example
It's hard to **teach an old dog new tricks**, but I'll try.
Es difícil **enseñar a un perro viejo trucos nuevos**, pero lo intentaré.