Hi @Paula22, sorry to hear about this!
I have translated your question 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.
Have you tried making sure that the main microphone is not covered by a protective case and that the port for the microphone is free from any dirt or lint. Also have you been able to carry out a quick test on the functionality of the microphones in the support app? Find and tap Settings > Support > Xperia Tests > Speakers & microphones.
Another thing that you can try is to reboot your phone in safe mode and try to record a video there. Safe mode is a troubleshooting mode where all apps downloaded from Play Store is temporarily deactivated and by doing this, 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.
If the behaviour of the secondary microphone persists in safe mode, I would suggest that you try to repair the software on the phone using Xperia Companion and your device will get the latest update at once. Keep in mind though that if you decide to do a software repair, all user data will be lost in the process, so remember to do a backup before the repair.
If none of these troubleshooting methods manage to improve the functionality of the microphone, the best thing to do is to get in contact with your local support team in order to have your phone examined and repaired by an authorized service center. If you have any questions regarding the service such as service routines, warranty and consumer laws, these kind of questions are best answered by your local support team as well, as they vary depending on which market/country you are located in.
I hope that helped, let me know if you have any further questions!
