You get the "old" look if you change the
All Layer combo box to
I suggest to use 10 Pixels, and only to the vertex. The same should be set in
Options -> Digitizing, snapping section, search radius.
BTW updating to QGIS 2.14.4 or 2.16 is not a bad idea. I'm not sure what bugs were fixed after 2.8.1 was released.