When you hover over a cell in Microsoft Excel, comments don't appear. This can be frustrating if you're trying to remember what a particular cell is for, or if you want to quickly check something without having to open the comment box. Here are some potential solutions:

1. Make sure that the Show Comments option is enabled. This can be done by going to File > Options > Advanced. Under Display options for this workbook, check the Show Comments box.
2. If comments are turned on and you're still not seeing them, try zooming in. Sometimes the comment box will be too small to see at the default zoom level.
3. If you're using a laptop or other device with a touch screen, try using your finger to hover over the cell. The comment should appear after a few seconds.
4. If none of the above solutions work, there may be an issue with your Excel installation. Try uninstalling and reinstalling Excel, or contact Microsoft support for further assistance.