Hey it's your first post. Have fun. Sounds like you have a bad receiver. I have two boating buds. 1 uses gt3. Works great. 2 uses futaba fm. Works perfect. I was using futaba fm. Worked perfect. I am using spectrum now with non marine receivers. Range is super short. Just got Spektrum marine receiver . Have not tried.
https://m.youtube.com/watch?v=EZXRDgwVX1w