The reason you might need less reaction / throw than you think is that the same amount of aileron throw has a much higher roll rate at high speed than at low speed. In fact if you think about it, for a given aileron angle, when you vary the forward speed, the roll rate is proportional to speed. The ailerons act like a screw going though the air and the faster you push it forward, the faster it rotates.
Without some coding and setup, CC3D doesn't have a way to sense the forward airspeed, but the faster you fly, the more sensitive (in airplane roll rate for a given stick angle) the ailerons are. If you set ailerons too sensitive you get oscillation at high speed, but OK at low speed. So you set the aileron sensitivity at max speed to avoid oscillation and you get slower controls at low speed.
So to work really well, you need airspeed (Revo class FC) to control the aileron (and elevator / rudder (unless rudder is unstabilized)) rates for high speed.
IMO, if you have rudder in addition to ailerons, the rudder should always be manual stabilization. If you have rudder with no ailerons (3 channel), the rudder should be set up in the FC as if they were ailerons (and use normal aileron stabilization).
Don't move the transmitter trims away from where they were when you ran transmitter wizard, or if you think you must, put them back there at the end of the flight and adjust using other methods that depend on the mode you were flying. You can make sure your trims are correct by looking at the Input page (with battery and USB connected) to make sure the "Channel Values" match the "Neutrals" for aileron elevator (and rudder only needed if stabilized).
A fixed wing beginner without access to an instructor probably wants to jump straight to Attitude mode because it self levels. Before first flight, you should check for reversed controls, adjust control linkages for neutral and range, verify CG, etc. A little bit nose heavy is a very good thing for Manual mode. It makes pitch positively stable (as opposed to neutrally stable) and it makes it so that (over the long term) adding power makes it climb and reducing power makes it descend.
You need to pay careful attention during setup that the FC thinks it is perfectly level when the airplane has wings very level and the fixed part of the horizontal stabilizer looks like a very very shallow (say 2 degrees) climb. Set all the control surfaces to neutral from Manual mode. I think there may be some issues, particularly if your elevator is out of trim and you have to hold constant elevator. You may find that you need to hold more and more because this needs to be adjusted with RotateVirtual, not with trims. Remember that for Attitude mode if you find you need to hold a lot of some control, the best thing is to quickly get it on the ground and adjust RotateVirtual before flying again.
In Attitude mode you will notice that the controls "wind up" a little once you start the motor. Because of this, you should launch fairly quickly after starting the motor. If hand launching, I would recommend that you hold the nose down slightly (elevator winds up "up" not "down"), but wings level till just before release.
In Attitude mode, during flight, remember that to turn it around you need to hold close to full aileron and full elevator through the whole turn. You can reduce altitude over the long term by reducing power. If it needs left/right trim, you might try rudder trim since it is not stabilized.
CC3D doesn't have INS13, but for people with Revo class FC's, know that the attitude level changes when you change from Basic to INS13. Either start with INS13 so you get leveling / RotateVirtual correct from the beginning, or redo RotateVirtual when you switch to INS13, or start by calibrating so there is no difference between Basic and INS13 ("Fine Tuning Your Hover To Stop Drift (Not Required)" in
https://librepilot.atlassian.net/wiki/display/LPDOC/Aux+Mag+Setup+and+Calibration).
Opinion: I find that you kind of need to be a good airplane pilot and knowledgeable LibrePilot user to set up a working Attitude mode in a fixed wing. First flight flown manually. Trim it out. Cross trim it for straight loops. Set control throws. Then fly in Rate mode and get that tuned and working well (airspeed PIDs for Revo class, and normal PIDs for all). Finally fly it in Attitude and get that tuned and working well. Then if you have a Revo class FC, you can start playing with GPS modes. A lot more work than Attitude mode with a quad.