One way is to go to your menu bar at the top of your web browser, click on "File" then "Print Preview". At the top of the window there should be a small window with "Shrink To Fit" in it. Click the arrow on that box for a drop down list and choose something, like 90% (there is a custom option at the bottom of the list if you need to set something unique in between what's listed) and see how it changes the print size of what is to be printed out and choose the one that looks and works best for you without cutting off text somewhere. This will make it larger when printed out.
Another way that usually works to make the print larger when printing internet stuff & emails is by changing the view size on the screen to a larger size in your web browser (this is separate from your other setting you've already setup). Go to the menu bar at the top (i.e. Internet Explorer), click on "View," then "Text Size" then select a size like "Larger" or "Largest" (something higher than what you're currently set to.)
Sometimes adjusting the current window's magnification (lower right corner of screen or Ctrl button + scroll wheel on mouse) can have an affect on print size.
The only other method is to copy & paste the text into a text editing software like Word and adjust the text size there. If you're using a text program, then you simply adjust the size of the text to a 12 or 14 point, or larger, font size (adjust depending on the font and size you need) and that should do the trick.
More info see this link.