Condition Cell

Maybe

Private Sub Worksheet_Change(ByVal Target As Range)

If Target.Cells.Count > 1 Or Target.HasFormula Then Exit Sub

    On Error Resume Next
    If Not Intersect(Target, Range("G11:G50")) Is Nothing Then
        Application.EnableEvents = False
       Select Case UCase(Target.Value)
       Case "F"
       Target.Value = "True"
       Case "T"
       Target.Value = "False"
       Case Else
       Target.Value = UCase(Target.Value)
       End Select
        Application.EnableEvents = True
    
    End If
    On Error GoTo 0
End Sub

VBA Noob