After installing a new font on Android phone, why is the SMS or part of the display of the system still the old system font instead of the newly installed font?

First, your mobile phone needs ROOT, and then you need to make sure that your mobile phone font is different from the font that comes with the system. You also need to make sure that you have overwritten your own fonts. If all three items are done, your mobile phone has not displayed the fonts installed in your heart and needs to be restarted.