Write cell to Excel- not write to defined cell/overwritten other coumns

Please help. I try to write to Excel on the process result that for this item has been process ‘completed’ for this row but RPA overwrite other columns (most are above rows and headers). Not sure if specify wrong cell or not.
Cell: “AA”+(RowIndex+6).ToString (To refer column AA in Excel/ row 7)
Capture Excel in yellow highlight are where RPA overwrite data. I want it to write to column AA7+ only

Thank you for your advice.