To highlight lines in an existing Excel document, click the "File" tab. Click "Open," browse to the spreadsheet and double-click it. Otherwise, Excel opens a new spreadsheet for you to use.

If the Signature Line option is greyed out in Excel or Word on your desktop, remove editing restrictions or add a signature line manually.

How to Insert a Logo in Excel. You can spruce up your plain and boring Excel spreadsheet by inserting a logo into the document. The logo can be aligned to fit the dimensions of any cell on the sheet.

Learn how to create, add or remove the digital signatures in the Microsoft Excel files. You will first need to have a signing certificate.