How to increase the volume of Redmi k30?

I recently encountered this problem and solved it by this method: 1. Enter the engine mode. Xiaomi/Redmi first opens the developer option: Settings-My Device-All Parameters-click 4 times in the MIUI version. Then enter "* #13411# * *" (without quotation marks) in the dialing interface to enter the engineering mode. Ps: If you can't get in, it may be caused by different brands and models of mobile phones. For example, some mobile phones need to enter "* # # 3646633 # * # *" (without quotation marks), some "* # # 2846579 # * # *" (without quotation marks), and so on. Second, the specific operation after entering the engineering mode, slide to the right, slide to the hardware test, and select audio. Familiar with several English phrases: Normal Mode Normal Mode Headphone Mode Speaker Mode Headphone Speaker Mode Headphone Speaker Mode Debugging Information Debugging Session Debugging Answer Audio Recorder Audio Recorder found "volume"-"audio playback" in the new interface; Find "System" in the new interface and click to enter; In the new interface, we can see three parts that need to be revised. Where Ring is the ringtone, Music is the media sound, and Accessibility is the call volume; The second option tab under "Ringtone, Music, Accessibility Interface" is the way to play sound; 3/4 polar headphones are headphones and speakers are external players. Set the 3/4 polar head data of ringtone, music and barrier-free interface in turn; Where (the value of index 0 ~ 15 corresponds to 1 ~ 16 grades of the scroll bar respectively, and the numerical range of each grade is 0 ~ 255). When the settings are completed, just click "Settings" without restarting the phone. When debugging, you can open a piece of audio and listen while debugging. After debugging, Xiaomi/Redmi remembered to turn off the developer option in the settings. (Settings-More Settings-Developer Options) III. refer to