It would have been helpful had you said you wanted to do that. Assuming these domain names are only in the hyperlinks, try:
Code:
Sub Demo()
Dim hLnk As Hyperlink
For Each hLnk In ActiveSheet.Hyperlinks
With hLnk
.Address = Replace(.Address, "domain.com", "xyzaddress.ca")
.TextToDisplay = .Address
End With
Next
End Sub
For anything else, you could use Find/Replace