Hello and welcome!
I have never experienced this with my Titan, but on other vehicles I have seen those symptoms be caused by low coolant level, clogged radiator, clogged heater core, bad thermostat, and bad water pump. Start by checking your coolant level. The radiator hose clamps are POS's, and tend to rust away leading to coolant or transmission fluid leaks because the hoses are loose. If the clamps are in bad shape, it is best to replace them with worm-style stainless clamps, especially the ones for the transmission hoses. The last thing you want is one of those hoses popping off the radiator and causing damage to your engine or transmission over a $0.25 hose clamp. One other thing I have seen on Nissan vehicles is the heater controller failing causing no heat, but since your problem goes away when you drive the truck, I think it is more likely related to the coolant system which supplies hot coolant to the heater core.