Due to the demands of cross platform development and the need for one product to be available and customised for different clients and/or devices, GameMaker Studio 2 includes configurations to make things simpler. Using this system, you can quickly switch between different splash screens, icons and included files and test or export only those that are relevant to the target platform or client at any time, all from the same base code.
To set up your configurations it is recommended that you first prepare a "default" config by incorporating all the configurable assets for the project into GameMaker Studio 2, including icons and splash screens (done through the Game Options), Included Files and any Extensions that you may need, and you can also go and change the output properties for sound resources or the texture group settings and many other options... Just about anything that can be configured in the IDE will be stored in the currently selected configuration.
Once you have set up the default configuration, you can then add a new one to the resource tree by right clicking on the configurations folder and selecting Add. Once that has been done, you can select the new configuration from the top of the resource tree and once selected, you can go ahead and customise them so that they change along with the configurations. For that you should now review the Game Options for each target platform and add, remove or change icons, splash screens and any other information that is relevant to the configuration, as well as set up the Texture Groups for each configuration. If you have set texture groups for each configuration you will also need to go through all the graphics assets (sprites and backgrounds) and re-assign them. Every change you make to these settings will be remembered by the configuration manager and recalled whenever you change configurations.
It is worth noting that you can have GameMaker Studio 2 automatically apply any given config to any given target platform. This is done by selecting the config you require for that platform from within the Targets Window. Once you have set a configuration to be used in this way, every time you compile to that target, either for testing or to create a final asset package, the configuration will be used. For more information on the Targets Window, please see the section on Compiling.