If you notice on your Android lollipop that the font size of SMS in the message app is very big, then you have accidentally activated the following settings: “change font size “
By pressing the Volume + or - key the text of the message either enlarge or shrinks. If you do not want to use on your Android Lollipop smartphone this feature, then we will explain how you can disable this feature in the settings. Please proceed as follows:
Open from the home screen: Menu --> Settings --> Section "Applications" -->Messages
In the next menu select now "Display". Now you can see the correct option already: "Change font size"
Remove here the hook to disable the changing of the font size using the volume keys. Finished!
Now you know why the messages were suddenly shown very large in the messages app on your on Android Lollipop smartphone.