Well there are a number of things you can do to improve your style:
- Create a PR video
- Ride a Taxi or a Gogoat
- Listen to the Audio Guide at the Museum
- Shop at various stores
- Get your Furfrou styled
- Take a train to Kiloude City
- Attempt to win the Lottery
- Test out your team at the Battle Institute
- Create Berry Juice at the Juice Shop
- Battle at the various resaurants
- Give your character a haircut or styling
- Have Alexa show you around
- Work for the hotel
I recommend working for the hotel, having Alexa show you around, and going to the Battle Institute. These activities have the most effect on your style.
If none of them work, your game could be glitches or something. I can't help you from there, though.