Originally Posted by ral
Okay. I figured it out. If Viber is off, it goes on when I get an SMS.
What do you mean "it goes on when I get an SMS". Do you mean a Viber text message, or a regular cellular SMS?
About Viber running in the background - this is actually what we recommend our users to do. Viber's battery and data usage when running in the background is negligible, and it improves the user's availability (over shutting the app off completely).
Viber's text font size should be the same on all phones, with slight changes that are probably caused by the phone's internal design settings.
About the option to change the text size: we invite you to enter our Feature Request page and post your suggestion there, or join an existing similar suggestion. The more people join on a request, the faster it will become reality
You can find it here: Have an idea for a new feature? | Viber Support