Almost impossible to choose selections in drop downs on reports

My browser is Google Chrome
I am looking at Cumulative Flow Diagram and want to change the time frame or Refine report - when I click on the little arrow a menu opens but I cannot move on to the options and change them. As soon as I move the mouse the menu disappears.
I face similar issue on Epic report, when I click on Epic drop down and want to change the epic, the drop down selection behavior is not normal.