Need to search cell for text string and paste text in based on finding

Maybe:

Sub Roland(): Dim ws As Worksheet, n As String, r As String, F As Range, frow As Long
Set ws = ActiveWorkbook.ActiveSheet: n = "AA": r = "AA/01"

    Set F = ws.Cells.Find(n)
    If Not F Is Nothing Then
    Cells(F.Row, F.Column) = r: frow = F.Row
        
        Do
            Set F = ws.Cells.FindNext(F)
            If F.Row > frow Then
                Cells(F.Row, F.Column) = r: frow = F.Row
                Else: Exit Do: End If
        Loop While Not F Is Nothing
    End If
             
End Sub