Hi @Ueeeee,
I'm sorry to hear this. 
I recommend that you try these methods. Verify whether there is any change in behavior after each method, before trying the next one.
- Make sure you have removed the temporary transparent protection film that covers the screen when you first buy your Xperia device.
- Check the touchscreen performance by using Diagnostic. To do so, go to: Settings > System > About phone > Diagnostics > Test > Touchscreen.
- Wipe the screen with a clean and dry cloth to make sure that your display is clean. Make sure that your hands and fingers are clean and dry before using the touchscreen.
- Remove any protective case, screen protection film or cover to verify it's not interfering with the touchscreen.
- Restart/Force restart your device. You can do this if you press and hold volume up and the on/off key simultaneously for at least 10 seconds.
- Disable Magnification gestures. You will find the option for this under: Settings > Accessibility > Magnification > Off.
- Reboot your device to safe mode to see if this behavior may be caused by one of your downloaded apps, as these are temporarily disabled in this mode
- Perform a software repair using Xperia Companion
Let me know if there is any change after trying these methods.