You’re welcome, David! the problem is that the symmetry feature had a slight rotation and it was not in one straight line with the end of the half of the glasses. Therefore, it is always better to make the end of the model at the zero point on the axis to which you will apply symmetry so that you do not need to move the symmetry axis because that will often not be accurate.
I tried to explain this in the attached videos. Please let me know if there is anything unclear.
thanks!