The phrase ‘set in your ways’ is used to explain someone who refuses to change.
Example in use: “I tried to explain the new plan’s benefits, but she’s set in her ways and refuses to listen.”
This phrase can be found in the early 1940 from: Collier's, Volume 106 Crowell-Collier Publishing Company "well, here it is," the McCoy tough guy explained. "We're from New York and you're from New York and we see you're okay. So we're out here for the fight. On business. The fix is in and the white boy wins.