RE: Forced upgrade Unified Interface
Step 2 complete
Run Powershell:
install-module Microsoft.Xrm.OnlineManagementAPI
$user = "username@here.com"
$password = "Password"
$cred = New-Object System.Management.Automation.PSCredential ($user, (ConvertTo-SecureString $password –ASPlainText –Force))
$namurl = "">admin.services.crm5.dynamics.com"
Get-CrmFlights -ApiUrl $namurl -Credential $cred

Note the ID of the flight with FS V7.x
Then run on the Instance ID you are changing:
Remove-CrmFlightAudience -ApiUrl $namurl -FlightId "6f02a010-5213-******-9ac3-d2d9620760ba" -InstanceId "9491da1a-e762-*************-e66bd9b8225a" -Credential $cred
Go to the portal and FS V8.x will be available.