It’s better to press according to the standard and chord chart, but it can be changed in the actual playing process, but not completely changed the chord, and no sound at all, because you did not try to vertical fingerboard between fingers when you were in the case, your finger belly touched other guitar strings, guitar guitar head slightly upward, so that your left hand is more comfortable, the wrist joint and thumb position of the left hand. Placement is very important. To know how to adjust the position of thumb, you will know that it is possible for me to follow the instructions when I play that chord. Instead of pressing the chord with four fingers at the same time when I change the chord, I should use the empty chord and the chord, when I change the chord, the right finger should play the line first, while the left hand should match the rhythm of the right hand, and it can be in the chord to be pressed. First, press the string and follow it up with the other fingers.