When you try to open a text file on your Redmi, you’ll probably see the below Complete action using prompt.
Here, you should select Remember this choice and tap Kingsoft Office. By doing so, you will open the text file with the pre-installed Kingsoft Office app, and you’ll not be seeing the same prompt again the next time you open a text file.
You should choose Kingsoft Office over Browser, simply because the former allows you to edit and save the text file.
Note: The steps here were written for MIUI V5, based on Android 4.2.2 on a Redmi (HM1W). If you’re having a different model of Redmi or other version of MIUI/Android, there’s a possibility that the steps and screenshots will be different.