In Excel Online, you can only view the rows and columns you transposed (or rotated) in the Excel desktop application, but the Paste Transpose option isn’t available to rotate rows or columns.
If you have the Excel desktop application, you can use the Open in Excel button to open your workbook and transpose the rows and columns there. Here’s how:
Click Open in Excel and transpose (rotate) data from rows to columns or vice versa.
Save the workbook and when you reopen it in Excel Online, the transposed data is available.
For news about the latest Excel Online updates, visit the Microsoft Excel blog.