I think you have to create a file named SkypeSettings.xml located at following path
Add following line:
Save the file then Restart the MTR device, If the file was deleted after restarting the change was applied.
Please remember that starting with version 4.17, the refreshed home screen design is enabled by default. The
</TeamsRoomsNewExperience> setting will be removed in a future release.
Have a good day.