Another option is to use the plugin: Maxima.

After selecting the dataset and sub-brick, and
then probably setting a threshold that is close
to your maximum value, you can run it. It will
dump RAI coordinates of the extrema to your
terminal window, along with the corresponding
dataset values.

You can then right-click on an image, and
"jump-to-xyz", entering the coordinates that
were output to the terminal.

There is also the option of providing a prefix.
If you do that, it will create a dataset with
spheres centered at the extrema surviving your
threshold (though that may not be something you
care for).

That plugin is very old, and may have some, um,
issues.... :)

- rick