Adobe Acrobat XI lets you edit text in PDF documents whether the document is scanned or converted from another program. The Content Editing tools are key to changing font size, color and other formatting in your PDF document. However, there are also some limitations on your ability to change font sizes.
Boxes will appear around lines or paragraphs of text in your PDF when Acrobat recognizes text. If these boxes do not appear, click "Tools," then "Text Recognition" and then "In This File" to open the options to recognize text. Choose which pages you want Acrobat to recognize text on and click "OK" to start the process. Newly recognized text may not use the same font as the original. If you want to retain a particular font, edit or recreate the document in another program and convert it to PDF, or manually change the font once Acrobat completes the text recognition process.
Changing Font Sizes
Click "Tools," then "Content Editing" and "Edit Text & Images." Select any text you want to edit, and the format options under Edit Text & Images will become available. Change the font size using the drop-down menu of numbers below the font name drop-down menu. This changes the position of other text within the current text box, but will not make room or close up empty space between any other text boxes.
When converting documents from a word processing, spreadsheet or desktop publishing program to a PDF, you may be able to choose to embed fonts so that the document will display the text using the original fonts, whether or not they are installed on any computer that may read the document later. However, not all fonts are licensed to be embedded. As a result, the document may appear improperly formatted on another computer. Even if you successfully embed a font, a computer without that font installed will not be able to change the size of text without changing the font itself. In such cases, Acrobat will substitute a similar font or its default font.
To adjust the position of text on the page after changing the font size, mouse over the box around the text until the mouse pointer changes to a four-way arrow. Click and hold, then drag the text box to the new location. You can also resize the text box by clicking and dragging the small squares at its corners.