Prevent New Instances of Excel 365

[pliskers]

I am trying to prevent Excel 365 from opening a new instance of the application when I double click on a file name in Windows Explorer. I've seen various solutions posted for earlier versions, related to the Option to "Show all windows in the taskbar", but that option does not appear to be available in Excel 365.

I get error messages from the opening of the second instance due to the presence of a Personal.xlsb file that holds my frequently used macros. I'd like all newly opened files to appear in the same instance unless I choose to open a second one.

Is there a way to prevent this from happening?

EDIT:
Just a follow up to be clear: If I use the File-Open method in Excel, the second file will open in the same instance. What I'm looking for is a way to prevent a second instance from opening when I have one file already open and double-click a second file in Windows Explorer. That's what I'm inquiring about.

 

[ranman256]

dbl-clicking the file outside of Excel will begin a new instance. Win-OS is doing it, not excel.

 

[Strithken]

This sounds like the "Ignore other applications that use Dynamic Data Exchange (DDE)" option is checked.

To uncheck this, use Application.IgnoreRemoteRequests = False or navigate to the option: File -> Options -> Advanced -> Scroll down to General Section -> Ignore other applications...

When you are double-clicking on the file in the File Explorer, Windows is using DDE to send data to the instance of Excel. If that value is set to True, the existing instance of Excel ignores the data and a new instance of Excel is opened (that's what's supposed to happen anyway... doesn't work for me). Any change in this setting is persistent (written to the registry when the application closes; I've observed it is not persistent when changed in Safe Mode).

 

[pliskers]

This sounds like the "Ignore other applications that use Dynamic Data Exchange (DDE)" option is checked.

To uncheck this, use Application.IgnoreRemoteRequests = False or navigate to the option: File -> Options -> Advanced -> Scroll down to General Section -> Ignore other applications...

When you are double-clicking on the file in the File Explorer, Windows is using DDE to send data to the instance of Excel. If that value is set to True, the existing instance of Excel ignores the data and a new instance of Excel is opened (that's what's supposed to happen anyway... doesn't work for me). Any change in this setting is persistent (written to the registry when the application closes; I've observed it is not persistent when changed in Safe Mode).

Exactly what I needed - thank you!

 

[CityGirl314159]

Hello,
I have the exact issue described in the original post. However, I confirmed that the "Ignore other applications that use Dynamic Data Exchange (DDE)" option is not checked.

And just to clarify: I recently received a new computer. This was NOT an issue on my old computer; I was able to double-click on a file name in File Explorer and the file was opened in the existing instance of Excel.

Any other ideas for how to prevent a new instance of Excel?

Thanks so much for any help that you can provide.