Adapted camera to resolution but not canvas.

I have added such script implemetation to my game ( https://answers.unity.com/questions/674726/different-camera-views-in-different-devices.html) but I still have 1 problem. Because of the images resize, the canvas resize doesnt fit the real game screen. See pictures as example:

This is the game when i set the native resolution: It's OK

Before playing I force free aspect and the canvas resize to fill the full size of the real screen alt text Then I press play and the game resize with the camera script but the canvas remains the same alt text

This is what happen when i change the resolution and I press play

¿Who can alfo fix this? or ¿There is another more elegant solution to have a game running with multiple resolution devices? Thank you