If you are seeing an older version of a SharePoint file, please follow the instructions below:
1) Open the program which is opening the wrong version of the file, in this case Excel.
2) Go to File > Open > Files Needing Attention.
3) You should see the offending file in the list. Depending on whether the file contains important data, you can either discard the local copy, or save the changes to a different file name.