Hi @Isabela2. let me see if I can help out here!
Your post has been translated to English as this is an International forum, please post any replies in English and it will be easier for me and other users to assist you.
There is no way to raise or lower the sensitivity of the proximity sensor in the settings of the phone.
Do you have a display protector mounted on your device, or any cover which could cover the sensor? Try removing it in that case to see if the behaviour persists. The easiest way to test the functionality of the proximity sensor is through the support app. Find and tap Settings > Support > Xperia Tests > Proximity sensor.
Another thing that you can try is to reboot your phone in safe mode to see if the behaviour of the proximity sensor persists there. Safe mode is a troubleshooting mode where all apps downloaded from Play Store is temporarily deactivated, thus you can see if this behaviour is caused by a downloaded app. For more information on safe mode and how to use it, click
here.
Try these measures and let me know how it goes!
