I was making a magic item and I put in the damage incorrectly by accident so I went to try and edit the damage but it won't let me, every time I time I click on the "modifier" tab it just tries to create a new one instead of letting me edit the old one 

Are you clicking edit on the existing modifier?

no theirs no option to click edit on the modifier its only giving me an option to add another one

Can you get us a screen shot or two of what you are seeing?

Yea but how do I send it to you? 

When you go back to edit item the modifiers section will be hidden showing only the header "modifiers" and the add button. If you click on the header but don't click the button it will unhide the section showing the modifiers - on the right-hand side of these will be Edit and Delete links.

thank you i have just seen that apparently my screen is just small enough that the very end column is off screen