You can quickly control this by typing built-in magic commands in Spyder's IPython console, which I find faster than picking these from the preferences menu. Changes take immediate effect, without needing to restart Spyder or the kernel.
To switch to "automatic" (i.e. interactive) plots, type:
%matplotlib auto
then if you want to switch back to "inline", type this:
%matplotlib inline
(Note: these commands don't work in non-IPython consoles)
See more background on this topic: Purpose of "%matplotlib inline"