Upgraded MFC application still looks old

You should at least add this line to your project, for example add it to stdafx.h

#pragma comment(linker,"\"/manifestdependency:type='win32' \
name='Microsoft.Windows.Common-Controls' version='6.0.0.0' \
processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"")

Or add the following to your manifest file:

<dependency>
    <dependentAssembly>
        <assemblyIdentity
            type="win32"
            name="Microsoft.Windows.Common-Controls"
            version="6.0.0.0"
            processorArchitecture="*"
            publicKeyToken="6595b64144ccf1df"
            language="*"
        />
    </dependentAssembly>
</dependency>

See also Enabling Visual Styles

It gets more complicated for owner draw controls. See this reference: Using Visual Styles with Custom and Owner-Drawn Controls

For ListView and TreeView controls, you can call this function for a more modern look (although it doesn't make any difference in Windows 10)

SetWindowTheme(m_ListView.m_hWnd, L"Explorer", NULL);
SetWindowTheme(m_TreeView.m_hWnd, L"Explorer", NULL);

_{* #pragma comment is Visual Studio specific. For other compilers you need to modify the manifest file}