From the menu at the top of the main program window, choose Setup | Reports and Forms, and choose the Receipt form that you want to use.

Sage 50 stores the 'form' information with the Company data file, so you can set up company X to print a different invoice form than Company Y, on the same workstation. Your Windows 8.1 system uses different directory naming than Vista did.

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The locations of forms and the names of printers are stored by user login ID and by form.    So there is a setting stored for each person's invoice, for instance (and no central management tool, unless you count hacking into the database.

Form parameters are a stored in the table tUserFRM.  The file and pathname is stored in sFormPath; the type of form (Sage 50 print, Crystal, Email) is in nEntType, the field lFormID is not documented.   This I know from rolling out form changes to 10 user Sage Quantum systems.  

If you have one workstation that's not working, it's either actually configured differently, or the Sage 50 user ID is configured differently from all the others, and / or Crystal Reports was installed on the old workstation and not on the new.   

Usually it's a user ID / company file combination where the form file set up is for old, old, old versions.   (i.e. it's still pointing to the 2008 invoice file on the oldest computer in the building, so the 2012 doesn't work because the 2008 wasn't installed on it.

This is a peer support forum, so nothing above is direct from Sage.  

Actually we migrated multiple computers and only one computer has issue

If I was there at the keyboard, I could probably tell you more. But even though I'm not, I've always found that when the software says '<pathname>\<fileIWant>' isn't there, that's what's wrong.

The solution is to do what the error message suggested - search for the filename, pick it, etc.

If you believe that the form really is where the setting points to, try copying all but the filename and pasting it into the Explorer address bar.