How much previous experience do you have with a 4 channel plus, two stick RC transmitter? The answer will have some bearing later.
The flight controller directs the ESC's to provide a proportional amount of power to the different motors based upon the commands being input at the RC controller. What happens when your fingers are off the sticks is determined by the state of trim the various channels are in. If, when checking channel settings, you find all are at "zero" when your fingers are off the sticks, the flight controller (FC) will be telling the ESC's (electronic speed controllers) to maintain position with the H. Essentially telling it to do nothing that would change what it is doing, but keep it where it is, as it is. Best time to check these settings is with the H on the ground with the motors off. It may drift a little bit in any direction due to wind effects but it will be generally stable. There will be no "twist" which is known as "Yaw", no Roll, or side to side motion, and no Pitch, which is forward and aft motion, and altitude will be generally maintained because the throttle stick would be in the center position.
The weight and pitch of the propellers will not matter unless there were extreme differences because the FC is telling each motor what speed they need to run at to maintain equilibrium. It will have each motor run at a completely different speed to maintain that state. That's pretty much how it all works even with perfectly matched props. It's a very, very rare event when all the motors would be running at the same speed.
When the H is close to the ground, say about 3'-5' or so, there is quite a bit of turbulence under it do to the down wash effects of the propellers. This will make the H "dance" just a little bit. That amount of movement is relatively small, and it is totally unreasonable to expect things to function absolutely smoothly when close to the ground. That's why experienced operators leave the ground and gain altitude quickly to rise out of the turbulent effect of the propellers at or very near ground level.
Back to that experience thing. If when you are flying you put the H into a hover about 12'-15' off the ground and take your hands off the sticks, does the aircraft yaw? If not then it is well trimmed and changes only occur when you command them. If you have activated the "cruise control" function you might have accidentally pushed one of the forward/aft, right/left trim buttons on the D pad and now have the H slightly out of trim but those trim pads do not input yaw. Worse case would have the H moving a little to one side or the other or forward and back with your hands off the sticks with no yawing motion. So we can rule out the trim pads as a possible cause of unwanted yaw. Now, while in that 12'-15' hover, put your hands back on the sticks and move the H one direction or the other a little bit while maintaining that altitude. Stop the movement but keep your hands on the sticks. Does the H now yaw? If so you found the cause, which I strongly suspect will be the case. The cause is you because your left thumb is applying just a little bit of side pressure on the stick. It does not take much to initiate and maintain a slow yaw.
While descending to land the H will not yaw unless it is being told to do so. When close to the ground the H will move from side to side and forward/aft a little bit because of prop wash turbulence, but it does not yaw. Practice, practice, and more practice is what overcomes this problem. Learn your transmitter, and a big part of that is learning how sensitive the sticks are to command input, where "center" stick is for each one, a position where nothing is changing because the sticks were not deflected enough to initiate a change. That location is very, very small, which means when you desire small amounts of change you need to apply very small pressure on the sticks, and do so slowly and smoothly. One of the most difficult things to learn in RC is how to fly straight and level. With multirotors that changes a little bit to flying a straight line in any direction. Why? because people new to the activity do not realize then when they think they are commanding straight line flight they are also inputting a little side control on the sticks when trying for that straight line. So their straight line looks more like a curve. Find your centers and learn how to remain within them.
It's not too hard, is fun, and just takes a little time and practice. Oh, don't mix propeller types. That's never a good idea because it forces the FC and ESC's to work harder. A lot harder. The only time a mix of propellers is used is on coaxial configurations (upper and lower motors on a single arm) where the top and bottom props might be of different sizes. However, all the tops will be of one size and type while all of the bottom props will be the same in another size and type.
