It sounds like the issue may be related to compatibility between the newer Excel 2007 format and the older Excel 97 format. When you save the file in the older format, some of the formatting options may not be supported or may not transfer correctly.

One solution could be to try saving the file in a different format that is compatible with both versions of Excel, such as the Excel 97-2003 Workbook (.xls) format. This format should allow you to retain your formatting changes while still being compatible with older versions of Excel.

To save your file in the Excel 97-2003 Workbook format, follow these steps:

1. Click on the "File" tab in Excel 2007.
2. Select "Save As" from the menu.
3. In the "Save As" dialog box, choose "Excel 97-2003 Workbook" from the "Save as type" dropdown menu.
4. Give your file a name and choose a location to save it.
5. Click "Save" to save the file in the older format.

Once you have saved the file in the Excel 97-2003 Workbook format, you should be able to open it in both Excel 2007 and Excel 97 without losing your formatting changes.

If this solution does not work, you may need to consider other options such as upgrading the older versions of Excel or finding a different file format that is compatible with all users.