@trevorc
you've still neglected to mention:
- the name of the sheet the Worksheet_Change event would be used on
- the column or range of cells the Worksheet_Change event would be restricted to
- the location (ie: starting column) where Sheets("Customer").Range("I" & t & ":L" & t) would be copied to
- the location (ie: starting column) where Sheets("Customer").Range("Y" & t & ":AH" & t) would be copied to

Posting a sample workbook would be to your advantage.