Can polygon feature on map have a thicker border line?

We are using ArcGIS 10.1. I have a feature (polygon) drawn on my basemap in ArcMap. When the feature was added to the map, ArcMap gave it a default color fill and line border color. If I go to the layer and change the color property, the polygon color in the TOC and on the map are changed. If I change the line thickness, only the border line for the layer in the TOC has a changed thickness. The line thickness for the polygon line on the map stays unchanged. Is there a way to increase the line (the border line around the polygon) thickness for the feature on the map and not just in the TOC?

Thanks - Peter