User wants to export a check to Microsoft Word in order to make some changes to it before printing.
This is not directly possible in CORE. However, as a workaround, you can use the Print Checks screen and print the check to a PDF file instead of a printer. Most modern browsers have the option to print as a PDF. For example, in Google Chrome, you can choose the option Save as PDF when printing. After that, you can open the PDF with Microsoft Word and edit it as needed. Check out this article from Microsoft support for details.