WPF NumericTextBoxDouble FontSize and AxisDouble exponential numeric format

Hi!

1.) How can I change the font size of NumericTextBoxDouble?

I use this code: 

<ni:NumericTextBoxDouble InteractionMode="ReadOnly" Height="50" Width="100" TextAlignment="Center" Value="999.999" FontSize="40"/>

but font size remain approximately 10-12 pixel.

Why?

2.) How can I disable the scientific (exponential) numeric format of the AxisDouble on WPF Graph?

Regards,

Tamas

P.S.: I use VisualStudio 2013 Community and MS 2015 Standard