Formula with File Location Reference Changes When File is Copied

A formula contains a file location reference, for example, 'c:\users\tom\library[MasterData.xlsx]Data'!B1

If the file is opened in Excel from the library folder, the address "c:\users..." is unchanged and the formula works.

If the file is opened in Excel from the library folder, saved on drive e: and then re-opened later, the address "c:\users..." is unchanged and the formula works.

However, If the file is COPIED to another location such as drive e: and then opened there, the address "c:\users..." changes to 'e:\[MasterData.xlsx]Data'!B1. Caveat: sometimes the reference is NOT changed. I don 't know why or how to duplicate it.

The address is treated as "Relative" rather than "Absolute."

Is there a way to make the address "c:\users..." absolute so that it cannot change?

Thanks in advance for your suggestions.