In October, I am flying from CVG to IAH for a 3 hour layover then to LAX. Both flights are on the same ticket and with same airline. On the ticket, it says there will be terminal changes. Will I need to recheck my bag through security or what will I need to do? I've never had a flight with a layover before.
IAH has a "Skyway" train that connects all the terminals inside security. Since you are traveling on one ticket, your checked luggage (if any) will be checked all the way through to Los Angeles, and you can confirm that with the agent when you check your bags in.
You'll be able to go to your gate for the second flight without going through security again. Just check the TV monitors to find the gate number for your next flight and follow the signs to get there. To change terminals, follow the signs to "Skyway" train and ride to the correct terminal.
Do not exit the secure area and take the "subway" train instead; that one is outside security.