Maybe you can try to include the boxes in a minipage or similar

\AMCOpen{lines=5}{ %
  \begin{minipage}{.4\linewidth}
    \wrongchoice[1]{1}\scoring{1}%
    \wrongchoice[2]{2}\scoring{2}%
    \wrongchoice[3]{3}\scoring{3}%
    \wrongchoice[4]{4}\scoring{4}%
    \wrongchoice[5]{5}\scoring{5}%
    \wrongchoice[6]{6}\scoring{6}%
    \wrongchoice[7]{7}\scoring{7}%
    \wrongchoice[8]{8}\scoring{8}%
    \wrongchoice[9]{9}\scoring{9}%
    \correctchoice[F]{f}\scoring{10}%
  \end{minipage}
}

Thanks - That does help to some extent. One of the problems is that the title of a box can get separated from the box on its left. I'll play around with it.