I use Mail, Safari, and Fantastical on my Mac in Full Screen view. However, I cannot seem to keep the full screen apps in the same location, e.g., in this order: Mail, Fantastical, Safari. When I use one of the apps they tend to move, e.g, Safari, Mail, Fantastical. Is there a way to “lock” the location of full screen apps in a desired order/sequence? “Show in desktop x” is not avaible when in full screen view.
Looking in System Preferences under Mission Control there is an option to Automatically rearrange Spaces based on most recent use. I would try unchecking it and see whether the spaces remain as required.
You can configure apps this way with TotalSpaces. Unfortunately, Apple has increasingly locked-down macOS for security reasons and in order to use this app now in Mojave you’d be required to turn off System Integrity Protection (SIP), which is not something I’d recommend. A shame, because TotalSpaces is a very cool and useful app.