I too find it awfully frustrating when getting a new eye wear, checking and checking if this fits or that fits better. Selecting glasses according to the shape of your face solves the issue.
Offset your round feature with geometric shaped glasses. Rectangular frames will help elongate your face, while cat eye frames will soften your feature.
Opposite of girls with round face, you should offset your shaper feature with curvier frames.
Lucky you! Oval shaped faces have the most wiggle room when choosing their eye wear. Like Rihanna, you basically get to wear whatever you want.
If you have a broad brow and narrow chin similar to Kylie Jenner, try a style with bottom heavy frame. Shapes that are parallel and extend past the with of your frame complement your jaw line.
I hope this tip helps