teach an old dog new tricks

Idioms  

1. Change longstanding habits or ways, especially in an old person. For example, His grandmother avoids using the microwave oven—you can't teach an old dog new tricks. This expression, alluding to the difficulty of changing one's ways, was first recorded in 1523 in a book of husbandry, where it was used literally. By 1546 a version of it appeared in John Heywood's proverb collection.

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Example Sentences

"Just because you're 'senior', let's say that, it doesn't mean the end - you can teach an old dog new tricks."

From BBC

They say you can’t teach an old dog new tricks.

From Washington Post

“Another driver in the series told me, ‘You can’t teach an old dog new tricks,’ and that’s kind of been his reputation his whole career in Europe,” Rahal said.

From Seattle Times

“As another driver in the series told me, ‘You can’t teach an old dog new tricks,’ and he’s had this reputation his whole career in Europe and we’re learning his reputation quickly here,” Rahal said.

From Seattle Times

You might save yourself some unpleasantness if you keep in mind the old maxim that you can’t teach an old dog new tricks.

From Scientific American