如何更改WPF中MenuItem的样式

我的TopLevelHeader的样式为MenuItem。这是默认样式，但当IsHightLight为True时更改背景除外。当我把鼠标悬停在它上面并点击它时，顶级MenuItem的背景将是红色的。

如何更改样式，使鼠标悬停在MenuItem上时背景为红色，单击MenuItem时背景为蓝色？

        <ControlTemplate x:Key="{ComponentResourceKey ResourceId=TopLevelHeaderTemplateKey, TypeInTargetAssembly={x:Type MenuItem}}" TargetType="{x:Type MenuItem}">
        <Border x:Name="templateRoot" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="true">
            <Grid VerticalAlignment="Center">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition Width="Auto"/>
                </Grid.ColumnDefinitions>
                <ContentPresenter x:Name="Icon" ContentSource="Icon" HorizontalAlignment="Center" Height="16" Margin="3" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="Center" Width="16"/>
                <Path x:Name="GlyphPanel" Data="{StaticResource Checkmark}" Fill="{TemplateBinding Foreground}" FlowDirection="LeftToRight" Margin="3" Visibility="Collapsed" VerticalAlignment="Center"/>
                <ContentPresenter Grid.Column="1" ContentSource="Header" Margin="{TemplateBinding Padding}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                <Popup x:Name="PART_Popup" AllowsTransparency="true" Focusable="false" IsOpen="{Binding IsSubmenuOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{DynamicResource {x:Static SystemParameters.MenuPopupAnimationKey}}" Placement="Bottom" PlacementTarget="{Binding ElementName=templateRoot}">
                    <Border x:Name="SubMenuBorder" BorderBrush="{StaticResource Menu.Static.Border}" BorderThickness="1" Background="{StaticResource Menu.Static.Background}" Padding="2">
                        <ScrollViewer x:Name="SubMenuScrollViewer" Style="{DynamicResource {ComponentResourceKey ResourceId=MenuScrollViewer, TypeInTargetAssembly={x:Type FrameworkElement}}}">
                            <Grid RenderOptions.ClearTypeHint="Enabled">
                                <Canvas HorizontalAlignment="Left" Height="0" VerticalAlignment="Top" Width="0">
                                    <Rectangle x:Name="OpaqueRect" Fill="{Binding Background, ElementName=SubMenuBorder}" Height="{Binding ActualHeight, ElementName=SubMenuBorder}" Width="{Binding ActualWidth, ElementName=SubMenuBorder}"/>
                                </Canvas>
                                <Rectangle Fill="{StaticResource Menu.Static.Separator}" HorizontalAlignment="Left" Margin="29,2,0,2" Width="1"/>
                                <ItemsPresenter x:Name="ItemsPresenter" KeyboardNavigation.DirectionalNavigation="Cycle" Grid.IsSharedSizeScope="true" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" KeyboardNavigation.TabNavigation="Cycle"/>
                            </Grid>
                        </ScrollViewer>
                    </Border>
                </Popup>
            </Grid>
        </Border>
        <ControlTemplate.Triggers>
            <Trigger Property="IsSuspendingPopupAnimation" Value="true">
                <Setter Property="PopupAnimation" TargetName="PART_Popup" Value="None"/>
            </Trigger>
            <Trigger Property="Icon" Value="{x:Null}">
                <Setter Property="Visibility" TargetName="Icon" Value="Collapsed"/>
            </Trigger>
            <Trigger Property="IsChecked" Value="true">
                <Setter Property="Visibility" TargetName="GlyphPanel" Value="Visible"/>
                <Setter Property="Visibility" TargetName="Icon" Value="Collapsed"/>
            </Trigger>
            <Trigger Property="IsHighlighted" Value="True">
                <Setter Property="Background" TargetName="templateRoot" Value="Red"/>
                <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource MenuItem.Highlight.Border}"/>
            </Trigger>
            <Trigger Property="IsEnabled" Value="False">
                <Setter Property="TextElement.Foreground" TargetName="templateRoot" Value="{StaticResource Menu.Disabled.Foreground}"/>
                <Setter Property="Fill" TargetName="GlyphPanel" Value="{StaticResource Menu.Disabled.Foreground}"/>
            </Trigger>
            <Trigger Property="ScrollViewer.CanContentScroll" SourceName="SubMenuScrollViewer" Value="false">
                <Setter Property="Canvas.Top" TargetName="OpaqueRect" Value="{Binding VerticalOffset, ElementName=SubMenuScrollViewer}"/>
                <Setter Property="Canvas.Left" TargetName="OpaqueRect" Value="{Binding HorizontalOffset, ElementName=SubMenuScrollViewer}"/>
            </Trigger>
        </ControlTemplate.Triggers>
    </ControlTemplate>

我这样更改触发器。但背景总是红色的，我把鼠标放在上面或点击它。为什么它不起作用？

<Trigger Property="IsChecked" Value="true"> <Setter Property="Visibility" TargetName="GlyphPanel" Value="Visible"/> <Setter Property="Visibility" TargetName="Icon" Value="Collapsed"/> <Setter Property="Background" TargetName="templateRoot" Value="Blue"/> </Trigger>

<Trigger Property="IsHighlighted" Value="True">
    <Setter Property="Background" TargetName="templateRoot" Value="Red"/>
    <Setter Property="BorderBrush" TargetName="templateRoot" Value="{StaticResource MenuItem.Highlight.Border}"/>
</Trigger>