If you are not getting resistance changes when using FulGaz for Windows 10, it may be that your smart trainer is not connecting via the correct channel. You can rectify this by turning on the "separate power meter support" option in Advanced Trainer Settings, then connect your trainer as both the trainer control source and also an external power source when pairing.
First, open your FulGaz app and un-pair your devices from the pairing screen, then continue to the main ride menu. Go into your settings (click the "cog" icon), then scroll down and select Advanced Trainer Settings. Check the tick-box next to Separate Power Meter Support.
Exit settings, shut down and re-start the app. You should then be given new pairing options when you open the app again.
Pair your smart trainer as both trainer control AND power.