I produced a map in ArcMap 10.3 with a point shapefile representing two types of values from its attribute table. One value is represented by symbol size, the other by color. For that I used the Symbology-->Multiple Attributes in the Layer properties dialog. I can not find a way to sort the points, so that smaller points are in front and bigger in the background. Situation now is that some bigger points overlay smaller ones in areas with point clusters. The proposed methods I found online are only working for unique values, like sorting the data or using symbol levels.