You want to update the firmware, as it does not suit you in terms of functionality.
Where can I find the firmware?
On the official website of the manufacturer.
On sites where developers post custom or official OS.
What should be done before installing the firmware?
Create a backup copy of all personal information: contacts, photos and transfer it to another computer.
Insert SD card. An SD card is needed to write firmware to it.
Determine your smartphone model.
Fully charge your device's battery.
Download archive with Firmware. Place it on the SD card.
Installing TWRP Recovery
Download the Official TWRP App to your phone from the Play Market. And install this app.
When you start the application for the first time, you must agree to install a new firmware and all the risks associated with this, as well as agree to grant the application Superuser rights and click the 'OK' button.
In the next screen, select the item 'TWRP FLASH' and provide the application with root-rights.
On the main screen of the application, click 'Select Device', and find your phone model.
After selecting the phone, the application will redirect the user to a web page to download the modified recovery environment image file. Download the proposed *.img file.
After downloading the image file, return to the main screen of the Official TWRP App and press the 'Select a file to flash' button. Select the file downloaded in the previous step.
Now press the 'FLASH TO RECOVERY' button and confirm your choice, press 'OK'.
When the message 'Flash Completed Succsessfuly!' appears on the screen. Click the 'OK' button. The TWRP installation procedure is now complete.
Write the firmware to the SD card. Using a PC or laptop card reader.
Insert a SD memory card into the phone.
To reboot into recovery, you need to enter the menu accessible by pressing the button with three stripes in the upper left corner of the main screen of the application. Select the 'Reboot' item, and then click on the 'REBOOT RECOVERY' button. The phone will reboot into the recovery environment automatically..
Firmware via TWRP
Before flashing, you need to delete all user data from the phone, this will avoid many problems. press 'WIPE' on the home screen.
You can start flashing. Click the 'Install' button.
The file selection screen is displayed. At the very top is the 'Storage' button, select the location where the firmware file is located.
Select the location where the files were copied. Press the 'OK' button.
Select the firmware file and click on it. A screen opens with a warning about possible negative consequences, you need to check the item 'Zip signature verification', which will avoid using damaged files during recording.
The procedure for flashing the phone will begin, accompanied by the appearance of inscriptions in the log field and the movement of the progress bar.
When the procedure for installing the firmware is completed, the message 'Successful' appears on the screen.