Do I need to pay taxes if I sell an alt coin for bitcoin then rebuy a different alt coin. I never took out actual USD so I am unsure how that would work. Or am I only taxes on actual USD made when I cash out?
It all depends on the country in which you are located, and what policy this country adheres to in the legislation on cryptocurrency activities.
There are countries in which cryptocurrencies are taxed and those where there is no tax on cryptocurrencies.