Controls don't return to their original position when switching between portrait and landscape

This is my

<Page
    x:Class="MyApp_WindowsStore.MainPage"
    xmlns="http://ift.tt/w9rHWX;
  xmlns:bm="using:Bing.Maps"
    xmlns:x="http://ift.tt/zZkFEV;
    xmlns:local="using:MyApp_WindowsStore"
    xmlns:d="http://ift.tt/PuXO1J;
    xmlns:mc="http://ift.tt/R4RR6u;
  
    mc:Ignorable="d" >

    <Grid Height="Auto">
        <Grid.Background>
            <ImageBrush ImageSource="Assets/Backgrounds/wallpaper.jpg" AlignmentX="Left"/>
        </Grid.Background>
        <Grid.RowDefinitions>
            <RowDefinition Height="140"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Canvas Grid.Row="0">
            <Canvas.ZIndex>
                1
            </Canvas.ZIndex>
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="120"/>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                <!--<Button x:Name="backButton" Margin="39,59,39,0" Command="{Binding NavigationHelper.GoBackCommand, ElementName=pageRoot}"
                        Style="{StaticResource NavigationBackButtonNormalStyle}"
                        VerticalAlignment="Top"
                        AutomationProperties.Name="Back"
                        AutomationProperties.AutomationId="BackButton"
                        AutomationProperties.ItemType="Navigation Button"/>-->

                <TextBlock Grid.Column="1"  x:Name="pageTitle" Text="App Title" Style="{StaticResource HeaderTextBlockStyle}"  
                        IsHitTestVisible="false" TextWrapping="NoWrap" VerticalAlignment="Bottom" Margin="0,50,30,0" >

                </TextBlock>

            </Grid>
        </Canvas>
        <ScrollViewer Grid.Row="1" Margin="0,-140,0,0"  VerticalScrollMode="Disabled" VerticalScrollBarVisibility="Hidden" HorizontalScrollMode="Enabled" HorizontalScrollBarVisibility="Visible">

            <!--<StackPanel FlowDirection="LeftToRight" Orientation="Horizontal" >-->
            <Grid x:Name="MainGrid">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition></ColumnDefinition>
                    <ColumnDefinition></ColumnDefinition>
                    <ColumnDefinition></ColumnDefinition>
                </Grid.ColumnDefinitions>
                
                <Grid Width="1024" Grid.Column="0">
                    <Canvas>
                        <Canvas.ZIndex>
                            1
                        </Canvas.ZIndex>
                        <TextBlock Text="Current" FontSize="32" Margin="117,130,0,0"  ></TextBlock>
                    </Canvas>
                    <StackPanel FlowDirection="LeftToRight" Orientation="Horizontal" VerticalAlignment="Bottom">
                        <Grid Height="400" Width="400" HorizontalAlignment="Left" VerticalAlignment="Top">
                            <Border Margin="-20,0,0,0" HorizontalAlignment="Left"  Width="300" Height="35"  BorderThickness="0.5" RenderTransformOrigin="0.5,0.5" BorderBrush="{Binding Path=PlotColor, Mode=OneWay}"  UseLayoutRounding="False" d:LayoutRounding="Auto">
                                <Border.RenderTransform>
                                    <CompositeTransform Rotation="270"/>
                                </Border.RenderTransform>
                                <ProgressBar Margin="0,-1.5,0,0" Style="{StaticResource ProgressBarStyle1}" Value="{Binding Path=Current, Mode=OneWay}" Foreground="{Binding Path=PlotColor, Mode=OneWay}" RenderTransformOrigin="0.5,0.5" >

                                </ProgressBar>
                            </Border>

                        </Grid>
                        <Grid Height="400" Width="400"  HorizontalAlignment="Left">

                        </Grid>
                    </StackPanel>
                </Grid>

                <Grid Width="900" Grid.Column="1">
                    <Grid.Background>
                        <SolidColorBrush Color="#FF0E0D23" Opacity="0.95"/>
                    </Grid.Background>
                    <Canvas>
                        <Canvas.ZIndex>
                            1
                        </Canvas.ZIndex>
                        <TextBlock Text="Forecast" FontSize="32" Margin="50,130,0,0"  ></TextBlock>
                    </Canvas>
                </Grid>
                <Grid Width="900" Margin="0,0,0,0" Grid.Column="2">
                    <Grid.Background>
                        <SolidColorBrush Color="#FF0E0D23" Opacity="0.95"/>
                    </Grid.Background>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="140"></RowDefinition>
                        <RowDefinition ></RowDefinition>
                    </Grid.RowDefinitions>
                    <Canvas>
                        <Canvas.ZIndex>
                            1
                        </Canvas.ZIndex>
                        <TextBlock Text="Location" FontSize="32" Margin="50,130,0,0"  ></TextBlock>

                    </Canvas>
                    <Grid Grid.Row="1" Margin="50,50,0,0" Width="700" HorizontalAlignment="Left">
                        <Grid.RowDefinitions>
                            <RowDefinition></RowDefinition>
                            <RowDefinition Height="200"></RowDefinition>
                        </Grid.RowDefinitions>

                        <bm:Map Grid.Row="0"  Margin="0,0,0,0" Credentials="ApLSRNznoDNW3KLuzC4AxVwBGl-bRwgtVkAXT-CehivBiGXTn_yXRIS01v2k93-f" x:Name="myMap"   ></bm:Map>
                        <Button Grid.Row="1" Width="75" Height="75"></Button>
                    </Grid>

                </Grid>

            </Grid>
        </ScrollViewer>
    </Grid>
</Page>

XAML