It’s easier if you know what you intend to do first. You can just select all the channels, link or Qlink them, then select and setup your insert (or other) effect and it will automatically do the same on all selected channels.
If you’ve already setup the effect in one channel, then select the other channels using alt click, then using the triangle pull down menu at the top rightmost corner of the mixer, select ‘copy first channels settings’, then again and this time select ‘paste to selected channels’. This will however indeed copy all channels settings.
If as above you’ve already setup the effect in one channel, but you only want to copy the particular insert effect, then select the other channels using alt click and then link the channels. Select the effect on the second selected channel and it will also appear on all selected channels. now go to the first channel and activate the effects window. Because all channels are linked, if you just do a tiny tweek of each of the controls (turn a knob 1 increment higher or lower then return it to it’s previous position) all the specific effects on all the other selected channels will spring to the same settings.
Don’t forget to de-link afterwards