I assume you are using 16.09 and what I describe is for that.
First of all you need to know that there is leveling and yaw being controlled in the default flight mode.
Second thing is that you should have the transmitter trims in the middle when doing transmitter wizard, and don't ever change the trims. Rate mode should simply be perfect. Attitude mode needs to be adjusted to stop drifting by changing Attitude -> Settings -> Rotate Virtual, but that can be done later if calibrations were done reasonably well.
Third thing is that the quad must be setting on a firm surface (does not have to be level) when you arm it. Don't hold it in your hand and arm it. It must be perfectly still. At this time (LED blinking quickly) it watches the gyros, assuming that the quad is motionless. Any rotation it sees it remembers to subtract that for the rest of the flight. This is called bias. That is how it handles trimming imperfect gyros (they all are).
The rest of this assumes the bias is correct so that when it thinks it is motionless, it is. If bias is not correct then the following is even more confusing.
For tilting in hand or on ground with motors running, the low altitude motors will run faster and faster until it gets level. This does not work well unless it is flying, because a small change in RPM does nothing. It would have to be enough change in RPM to lift the weight of the low side, not just move it "without effort" like in the air. One way it does work is if your quad does not have landing gear and just wobbles around easily on the center hump of the quad.
If it is not perfectly trimmed for the current bank angle (and it never is mathematically perfectly trimmed) then some set of motors will spin faster and faster.
Now throw yaw into the mix. If yaw trim is bad, then one diagonal set of motors get faster and faster while the other diagonal set gets slower and slower.
It is very difficult to hold it in your hand with the bank angle perfectly level and also with the yaw where it was when you armed it. Without that, the motors will be a confusing mess of speeding up and slowing down.
All this stuff works well in the air because there is nothing keeping the quad from rotating to where it needs to be.
I suggest that you carefully run all the calibrations (except mags since you have CC3D) in the Attitude tab.
For flying it should be level (not on sloped ground), and you should arm and immediately take off. Try to be off the ground in 5 seconds or less so the motors don't "wind up".
For a first flight, just blip the throttle up a tiny little ways and immediately back down. Then try again blipping a little more. Etc. You will finally get to the point where it jumps up a little. Either it tries hard to flip over (ESCs plugged in wrong, wrong props, wrong motor spin direction, etc.) or doesn't try to flip over (all that stuff is correct). If it doesn't flip, try a longer blip but don't let it get above knee or waist high. Try to control it a little when in the air, but first you must learn to maintain knee high altitude.