WPF MUI How to unload a user control and load another one

I got a plain MUI Main window:

<mui:ModernWindow x:Class="NeoClinic.MAS.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:mui="http://firstfloorsoftware.com/ModernUI"
        Title="PAMACQUAS" IsTitleVisible="True"
        LogoData="F1 M 24.9015,43.0378L 25.0963,43.4298C 26.1685,49.5853 31.5377,54.2651 38,54.2651C 44.4623,54.2651 49.8315,49.5854 50.9037,43.4299L 51.0985,43.0379C 51.0985,40.7643 52.6921,39.2955 54.9656,39.2955C 56.9428,39.2955 58.1863,41.1792 58.5833,43.0379C 57.6384,52.7654 47.9756,61.75 38,61.75C 28.0244,61.75 18.3616,52.7654 17.4167,43.0378C 17.8137,41.1792 19.0572,39.2954 21.0344,39.2954C 23.3079,39.2954 24.9015,40.7643 24.9015,43.0378 Z M 26.7727,20.5833C 29.8731,20.5833 32.3864,23.0966 32.3864,26.197C 32.3864,29.2973 29.8731,31.8106 26.7727,31.8106C 23.6724,31.8106 21.1591,29.2973 21.1591,26.197C 21.1591,23.0966 23.6724,20.5833 26.7727,20.5833 Z M 49.2273,20.5833C 52.3276,20.5833 54.8409,23.0966 54.8409,26.197C 54.8409,29.2973 52.3276,31.8106 49.2273,31.8106C 46.127,31.8106 43.6136,29.2973 43.6136,26.197C 43.6136,23.0966 46.127,20.5833 49.2273,20.5833 Z"          
        ContentSource="/Pages/Home.xaml"
        WindowState="Maximized"
        WindowStartupLocation="CenterScreen"
        Closing="Window_Closing">

    <mui:ModernWindow.MenuLinkGroups>
        <mui:LinkGroup x:Name="Pamakwas" DisplayName="Welcome">
            <mui:LinkGroup.Links>
                <mui:Link DisplayName="Home" Source="/Pages/Home.xaml" />
                <mui:Link DisplayName="Configurations" Source="ConfigurationsList.xaml" />
            </mui:LinkGroup.Links>


        </mui:LinkGroup>
        <mui:LinkGroup DisplayName="settings" GroupName="settings">
            <mui:LinkGroup.Links>
                <mui:Link DisplayName="software" Source="/Pages/Settings.xaml" />
            </mui:LinkGroup.Links>
        </mui:LinkGroup>
    </mui:ModernWindow.MenuLinkGroups>



    <mui:ModernWindow.TitleLinks>
        <mui:Link DisplayName="settings" Source="/Pages/Settings.xaml" />
    </mui:ModernWindow.TitleLinks>

</mui:ModernWindow>

first is the , the word "Welcome" is always converted to lowercase. How can I disable that?

2nd, as you see in the:

<mui:LinkGroup.Links>
                    <mui:Link DisplayName="Home" Source="/Pages/Home.xaml" />
                    <mui:Link DisplayName="Configurations" Source="ConfigurationsList.xaml" />
                </mui:LinkGroup.Links>

I got 2 Sources, If I click the Configurations, The DataGridView of my table is loaded (a UserControl), there is a NewEntryButton in that UserControl. I want it to unload the DataGridView UserControl if the NewEntryButton is pressed, but I don't know how to unload and load another UserControl in that same Link.

Please show me a xaml version (if there's any) and a C# code version(if there's any)

Solution

To navigate to a different page by code you can use

NavigationCommands.GoToPage.Execute("/Pages/MyPage.xaml", this);

In XAML you use a BBCodeBlock

<mui:BBCodeBlock BBCode="[url=/Pages/MyPage.xaml]go to my page[/url]" />

like explained in the documentation.

AFAIK navigating to a new page does not "unload" the previous one. The page (UserControl) is still alive in memory. Nothing to worry about until your application has hundreds of pages.