more updates to QT build instructions (#562)

Author: jw098

SerialPrograms/BuildInstructions/Build-Windows-Qt6.8.3.md

@@ -98,8 +98,9 @@ If you have already have older versions of Qt installed, but need to upgrade Qt
 - Under `Kits` tab, choose the newer Qt version (e.g. Desktop Qt 6.8.3)
 <img src="images/QT-kits.png">
 
-- Under `Compiler`, set it to Microsoft Visual C++ Compiler, if not already set.
-- Click `Ok`.
+- Under `Compiler`, set it to Microsoft Visual C++ Compiler or Visual Studio, if not already set.
+    - If you recently installed new compilers, go to the `Compilers` tab, click `Re-dedect`, then click `Apply` in the bottom right. Back in the `Kits` tab, your newly installed compilers should now show up in the list of compilers.
+- Click `Ok`, to save Kits preferences.
 - Click the Monitor symbol at the bottom left
 <img src="images/QT-kit-build.png">