How do I change default excel extension in Excel 2007?

Question

I'm getting hard drive images from someone that I am tweaking with my own software. But, The image has Office 2007. I've noticed that when I try and save an Excel document, it defaults to *.xls, not the newer *.xlsx extension that I want. Now, I've searched online and everywhere I look, it says

1. Click on the office icon.
2. Select Excel Options button.
3. Select Save from the left pane.
4. Select the extension under the "Save files in this format:" drop down.
5. Select OK.

I do all this and doing a save will default to *.xlsx extension. However, when I close and reopen excel, it's back to square one--defaulting to *.xls. Any ideas?

Answer 1

From what I understand, it may be set as part of the group policy: (see here)

In the left pane of the Group Policy Management Console, double-click User Configuration, and then double-click Administrative Templates (Classic Administrative Templates (ADM) in Windows Vista). Then follows the following steps to set and change the default saving file format in Office 2007 programs.

To change default file save options in Office Excel 2007

Double-click Microsoft Office Excel 2007, double-click Excel Options, and click Save.
In the right pane, right-click Save Excel files as, and select Properties.
In Save files in this format, select Enabled.
In the drop-down box, select a default file save format.
Click Apply to save the settings.