When upgrading from one version to another, the more code changes are in the new version, the harder / less likely that it will "just work".
The simple way to use your old settings is to make screen captures of the old settings with old GCS and put the same numbers into the new settings (new firmware, new GCS).
UAV files (File -> Export UAV Settings) are human readable text and can be edited with a text editor. So a more complicated way involves doing a three way edit with old setttings, new default settings and (create) new settings. It would take a lot longer to explain how than to do the screen captures.