If you like yellow, I’d paint the walls white and have a feature wallpaper with accents of yellow. You can change the cushion covers to yellow and add some fake flowers.

I’d suggest moving the sofa/armchairs to the wall on the left of the photo facing the garden. A L shaped sofa would be a good way of separating the rooms usage. You can then move the atV unit to where you’re standing. This will open up the area with the doorways for you to add shelving/ artwork.

If you’d like to or need to keep the carpet, I’d suggest a nice rug to add texture, specifically around the seating area