Is there a way I can make the font size smaller on default messaging app of LG L70 I have a rooted LG L70 (D325) and I want to make the font size of default messaging app smaller. I changed the font size on the settings but it is quite large to me that the person beside my can read my conversations so I want to change it to maybe 10px or smaller. 

I switched to different messaging app but delays send/receive messages.
I also want the popup message on the stock SMS App so I can reply easiy. (Similar to the image below, sent by 9122)



Can you please help me how to change it or at least suggest an SMS app that does the same as Pop Up Reply with font customization.
You can try using Textra SMS messaging app. It has options to customize the fonts smaller and change the text color. And you can also reply to messages quicky from the popup of received message. To make text smaller in Textra open Textra SMS's

Settings > Customize Look > Text Size > Smaller