1. Ensure that you have the Start - Run command.
    If you click the Start menu and don't see a Run... option, right-click the Start button and select Properties. Click the Customize... button, then scroll down the list (it's alphabetical) until you see "Run command". Check the box next to it, then click the OK button.

  2. With Excel closed, run the Regedit program.
    Click Start - Run... and in the box, type regedit and click OK. You should see a dialog with "Registry Editor" at the top, and a hierarchical outline or "tree" in the left pane - much like File Explorer, but for Registry settings instead of files.

  3. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\Configuration.
    Click the "tree" elements in the left pane to navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\Configuration -- just as you would in File Explorer. Your left and right panes should appear very similar to the screen shot below. (If you can't find this path, or you don't see at least a CDNBaseUrl entry in the right pane, don't make any changes - stop and get help.)

  4. Change the CDNBaseUrl entry to the Monthly Channel.
    If your Office 365 subscription is on the Semi-Annual Channel, you should see http://officecdn.microsoft.com/pr/7ffbc6bf-bc32-4f92-8982-f9dd17fd3114 as the value of the CDNBaseUrl entry in the right pane. Click this CDNBaseUrl entry to select it. Now, use your mouse to select (don't click) all of this string: http://officecdn.microsoft.com/pr/492350f6-3a01-4f97-b9c0-c7c6ddf67d60 and use Ctrl+C to copy. Then in the Registry Editor, select Edit - Modify..., and immediately use Ctrl+V to copy this string as the replacement data. Then click OK, and confirm that the CDNBaseUrl entry now shows the new string. Then click File - Exit to close the Registry Editor.

  5. Start Excel and ask it to "Update Now".