The shear center is related to the cross section of the shape. A wide flange has a shear center located in line with the centerline of the beam/web while a steel channel has a shear center located some small distance off of the web, on the opposite side from where the flanges point.
Loads applied to shapes will create a shear flow through the section. IF the section is symmetrical, the shear flow is balanced and the loading should be placed on the centerline of the beam. For the channel, the shape is not symmetrical and the shear flow progresses from the tip of one channel, across and down the web, and then to the top of the opposite channel. This produces an unbalanced torsional moment. If the load is placed at the shear center, the load x shear center distance moment exactly balances the shear flow moment in the section.
This is basic mechanics of materials and as an engineer you should know this stuff.
