Hi RachieA
If you right click on the file > Properties ...........is "Read Only" checked ?
Word 2010 is totally compatible with 2007 and you should be able to edit it.
Word 2010 default is to save as .docx extension which some of your customers may not be able to read if they have Word 2007 or earlier.
You can, however, alter this in Save As to Word97 - 2003 which is .doc extension.