Override custom color

for overriding custom color like

<SolidColorBrush x:Key="xcolor"
                 Color="#6D9DFF" />

redefine the same SolidColorBrush with the same Key

 <!-- using resource -->
        <Border BorderBrush="Black"
        BorderThickness="1"
        HorizontalAlignment="Left"
        Height="43"
        Background="{StaticResource xcolor}"
        Margin="366,177,0,0"
        VerticalAlignment="Top"
        Width="116" />
        <!-- redefine resource -->
        <Grid Margin="366,225,0,0"
              HorizontalAlignment="Left"
              Width="116"
              Height="43"
              VerticalAlignment="Top">
            <Grid.Resources>
                <SolidColorBrush x:Key="xcolor"
                                 Color="red" />
            </Grid.Resources>
            <Border BorderBrush="Black"
                    BorderThickness="1"
                    Background="{StaticResource xcolor}" />
        </Grid>