|It depends on the format of the document after it was scanned in.|
If it has been scanned/stored as an image (jpg, png, bmp, etc.) then you might have to edit it with some type of photo software, like PhotoShop, etc.
PowerPoint can be used to a certain extent, but it's certainly not as full featured as dedicated photo-editing apps.
If it is text document that has been scanned in via an OCR (Optical Character Recognition) application, then you might very well be able to edit the actual text.
I've even scanned text documents in as images and then added text boxes over existing "text" to get it to look like I wanted it to.
Gives us some more details about your requirements and we'll see if we can help more.