When you have lots of data on a workbook and it is spread out over the page with some blank columns or rows, a great way to select and highlight all your data is to use the CTRL+SHIFT+END keyboard shortcut.
This will extend the selection to the last used cell on the worksheet (lower-right corner).
John Michaloudis is a former accountant and finance analyst at General Electric, a Microsoft MVP since 2020, an Amazon #1 bestselling author of 4 Microsoft Excel books and teacher of Microsoft Excel & Office over at his flagship MyExcelOnline Academy Online Course.