I am researching flights on United out of George Bush in Houston to Argentina. Arrival into IAH (from a local airport) gives about an hour layover before leg to Panama City PTY. We will have to change terminals in IAH (international terminal). Will there also be security here? Is there any type of immigration or addition screening when you leave the US? For infrequent international travelers, I worry an hour isn’t enough. Other option allows 3 hours. Thanks!