If I turn the steering wheel 20 degrees is not return to the center, I tested it with the low and high speeds, someone told me that in electric steering this is normal and it is not a problem, is it true?
Most probably, you need an alignment. The part of alignment which causes your wheel to return to center is called caster (the other two major portions of alignment are toe-in and camber). Here is a representation of the caster alignment:
This website gives a pretty good explanation of caster and how it affects driving in your car:
When you turn the steering wheel, the front wheels respond by turning on a pivot attached to the suspension system. Caster is the angle of this steering pivot, measured in degrees, when viewed from the side of the vehicle. If the top of the pivot is leaning toward the rear of the car, then the caster is positive, if it is leaning toward the front, it is negative. If the caster is out of adjustment, it can cause problems in straight line tracking. If the caster is different from side to side, the vehicle will pull to the side with the less positive caster. If the caster is equal but too negative, the steering will be light and the vehicle will wander and be difficult to keep in a straight line. If the caster is equal but too positive, the steering will be heavy and the steering wheel may kick when you hit a bump. Caster has little affect on tire wear.
If your steering wheel is not turning back to center after a corner, you probably either not enough, or negative caster.