A key with many jobs:
Press the Text Key and see all the different choices you have. You will find it on the bottom row of your keyboard, just to the right of the spacebar key. Everything in this dialog box is related to text on your screen or how you see text (and other things) on your screen. Use the up, down, left and right keys to navigate this area, and the center button (press in) to make what you have selected happen.
You can adjust the text size, typeface (K3), line spacing, and number of words per line. You should have no trouble finding just the right setting for your personal needs or tastes. It will stay that way until you change it again.
You will also find the Text to Speech (on or off), zoom into pdf documents, adjust their contrast (K3?) and change the screen rotation settings to suit yourself.