Hi there! I can definitely help you with changing the default folder when opening files in Excel 2007.

Here are the steps to change the default folder:

1. Open Excel 2007.
2. Click on the Office button in the top left corner of the screen.
3. Click on Excel Options at the bottom of the menu.
4. In the Excel Options window, click on the Save tab.
5. Look for the Default file location field and click on the Browse button next to it.
6. Choose the folder you want to set as the default folder for opening files.
7. Click OK to save the changes.

Now, when you go to File Open, you should be directed to the folder you set as the default.

If you're still having trouble, it's possible that the accounting program you installed changed some settings in Excel. In that case, you may need to uninstall the program or contact their support team for assistance.