How can I reset MIUI 11 features? I turned off MIUI optimization and some features were lost and I can't retrieve them after I turn it on again.
You need to enable Developer options on your MI device.
To unblock the developer options, 


Go to Settings >About, find the MIUI version and tap 7 times continuously.
You could see a message “You have enabled developer option” once you have successfully done that. 
To access developer options, Goto Settings > Additional settings > Developer options. 
Now scroll down till the end to see the option to toggle MIUI Optimization. You’ll need to restart the device once you enable the option.


Even though it is just a toggle which we enable, it causes the way which the system behaves, in turn changes the way many apps behave.



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