Hi edurden,
I'll start with the answer to the first question, since the info in question 2 isn't quite enough to give a real solution (for me, at least).
For your multi-file update, I've also made some assumptions:
1) Your data files are all in the same directory "test", which is a subdirectory of your "current" directory
2) They have an xls extension
3) They are the only excel files in the directory
4) The tab with the cell you want to change is called "DataTab"
5) The cell to be updated is A1
6) The new value is "newvalue"
Modify those elements in the following code appropriately to reflect where the files really are, the tab name, and the cell to be updated.
Code:
Sub UpdateFiles()
MyDir = ActiveWorkbook.Path
DataDir = MyDir & "\test\"
ChDir (DataDir)
Nextfile = Dir("*.xls")
While Nextfile <> ""
Workbooks.Open (Nextfile)
Workbooks(Nextfile).Sheets("DataTab").Range("A1") = "newvalue"
Workbooks(Nextfile).Save
Workbooks(Nextfile).Close
Nextfile = Dir()
Wend
End Sub
Hope this provides a starting point,
Cindy