problem mobile view content sidebar

Hi,
I have the Problem, that the view of the Content sidebar of my website (right sidebar) is not shown up on mobile devices.

The desktop view is ok. On the smartphone (Samsung, Android) the right sidebar disappears. As there are positioned important parts of the Website (such as search field, additional menu, table with grafic Buttons) it is really needed to be seen.

I use 2014 with 3 columns. The left sidebar and the main content are ok. The Problem is only the right column.

Pls. can anybody help me?

Thanks for your help in advance!

Reg. Kramar