Can't edit Textblock content in WPF

I'm working on my first WPF application and I notice that I'm not able to edit the text values in any of my textblocks. I can't seem to find anything wrong here that would prevent me from changing it... ``` <Label Content="Line Terminator" Grid.Row="0" Grid.Column="0" Margin="5"></Label> <Border BorderThickness="1" BorderBrush="LightBlue" Grid.Row="0" Grid.Column="1" Margin="5"> <TextBlock x:Name="txtLineTerm" Focusable="True" IsManipulationEnabled="True" Padding="3"></TextBlock> </Border> <Label Content="Field Terminator" Grid.Row="0" Grid.Column="2" Margin="5"></Label> <Border BorderThickness="1" BorderBrush="LightBlue" Grid.Row="0" Grid.Column="3" Margin="5"> <TextBlock x:Name="txtFieldTerm" Focusable="True" IsManipulationEnabled="True" Padding="3"></TextBlock> </Border> ``` Can anyone see the problem? I feel like there's a concept that I'm missing here. Any explanation will be greatly appreciated.