There were times when I had to edit a map or a certificate, hence here are some trick I use.
In Acrobat 9 you can change a PDF to a PNG.
First open the PDF(hopefully it’s an 8.5’ x 11” page).
Next, go down file and choose save image as png.
In Acrobat 9 you can change the PNG to a PDF and then write anything here.
Open Acrobat, then choose the png file to convert to a PDF. Next, go to comments and choose the text tool. Highlight the area you want to write something on that spot. You can adjust the size and color of the writing by opening another window by using the CTRL/E keys(the text box tool properties window appears), then type. Next, choose save as PNG or PDF by going to the file menu and clicking on image.
In Acrobat 9 you can change a PNG to a PDF and back to a PNG then block out previous writing and rewrite over them. Open Acrobat, then choose the png to convert to a PDF. Next, go to comments and choose the text tool. Then hold down the keys CTRL/E and the text box tool opens. Choose white for the color and highlight the area to block out. Now type the correction(you can choose a color for typing after blocking out the area by holding down ctrl/E)! Choose save as PNG or PDF by going to the file menu and clicking on image.
In Acrobat 9 if you have a scanned PDF and can’t do the above, then open it and go to file and choose image save as png. Next do any of the above!