I don't understand what this message is for. I've never merged files and I don't want that. And I don't want to accidentally merge files. So please tell me how to switch this annoying message. 

Hi,

May I know which version of Office you are using, and which Office application you are using when you see this message?

I've seen this occurs a lot in some old versions of Office, such as Office XP, Office 2002... Generally with Word files which were sent as attachments in Outlook.

In Outlook, check the following option:

Tools | Options | Preferences | Email Options | Advanced, uncheck the box marked "Add properties to attachments to enable Reply with Changes." Save the setting and check if this issue persists.

Regards,

Melon Chen
TechNet Community Support

• Marked as answer by Melon Chen CHNMicrosoft contingent staff, Moderator Monday, June 23, 2014 1:56 PM

Hi,

May I know which version of Office you are using, and which Office application you are using when you see this message?

I've seen this occurs a lot in some old versions of Office, such as Office XP, Office 2002... Generally with Word files which were sent as attachments in Outlook.

In Outlook, check the following option:

Tools | Options | Preferences | Email Options | Advanced, uncheck the box marked "Add properties to attachments to enable Reply with Changes." Save the setting and check if this issue persists.

Regards,

Melon Chen
TechNet Community Support

• Marked as answer by Melon Chen CHNMicrosoft contingent staff, Moderator Monday, June 23, 2014 1:56 PM

I get the same message when I open a 2013 Word Doc.  The original doc was received via Outlook 2013.

I'm on Outlook/Office 2013 so don't have the same path you have given above.