Scanning is the equivalent of taking a photo of a document, and Word is not a photo editor. What you will need to do is find a program such as Acrobat Professional* that lets you extract the text from the scan. Then you can put the text into a Word file and adjust it as required. Depending on the quality of the original document, this can be a fairly tricky operation … Good luck!

* assuming the result of the scan is a .pdf; I don't know what you'd be best off with if the scan is in another format