The buttons (icons) on the Acrobat Toolbar are especially helpful when working with online forms. They are from left to right:

Save File... Allows you to save the open file to your computer. This is an easy way to save a copy of the application to fill-in later or just to make a copy for your records. 

Magnifying Glass...Turns your cursor into a magnifying glass to increase the size of the page to make viewing easier. 

Page Controls... Flips through the pages in the application. The outermost arrows w/lines take you either to the first (left) or the last (right) page in the document. The other arrows page back or forward. 

Page Size Controls...These icons determine the viewing area of the page. From left to right; the first icon will set the page to the actual size (100%), the middle icon fits the entire page into the available window; and the last icon will adjust the page to fit the width of the available window. I recommend that you maximize your browser window by clicking on the center icon or the Browser Toolbar and then select the last icon on the Acrobat Toolbar. This will make the application the largest your computer is capable of.