I have an Android, a Galaxy S3 and wanted to decrease the size of the displayed font. One of the ways to do so is to go to settings and select an option that allows the user to change the font size via the volume controls. I've wondered more than once whether this was overloading the UI - especially as there was no indication on the screen that the volume was the font-size controller. (And of course a link from this indicator to the settings control.)
Low and behold I overheard someone on the subway speaking to a friend that the font-size on his messages had zoomed too large and he didn't know why that happened or how to change it back to the default settings. I was able to change it for him. Somehow he had gone to settings and selected this without knowing. To add more pain to the situation the menu associated with messages does not provide the user with a means of changing font-size.
The lessons to be learned? When overloading UI controls give an indication to the user what is being done and link back to the admin section to allow the user to change the settings. And second provide multiple ways to change the settings. It can be as simple as a "more" link.