2009 Opps file association

I have New Era platinum and jumped on the band wagon for the free 2009 release.

In doing so the 2009 install changed my default T:ane cdp file action (open and install) from T:ane to the CM in 2009.

I tried to change the file association via the open with feature in Win10 but nothing changes. Put in a trouble ticked and support says it can’t be changed back to T:ane without doing a regedit in Windows. They refused to tell me how for fear of messing with my registry.

I am quite comfortable in working with regedit but I’m not sure what and where I need to change.
Can Anyone tell me what area needs to be changed?

Thanks.
Don

Fallnflag - Yes; the change in file association for CDPs was indeed an unwelcome side-effect from installing the gifted TRS2009.
And Windows 10 recent changes to the settings dialogs to set or change file associations is annoying too. It shows the current association (TRS2009 Trainz.exe) and Microsoft Store as the only choices available, without the option to choose your preferred file association.
All is not lost, however.
I was able to add Tane.exe to the association list by using the 'Open with...' feature when selecting an existing CDP file. The association for Tane.exe then became available - and could be set - from the Default Programs settings area.
Suggest try again.