Using this feature can be helpful for checking girder loads or having to add loads by hand.
To use this feature go to notes on the top of the toolbar.
Then choose to add all reactions by clicking on the auto reactions tab. (This setting can be a bit overwhelming as it adds all reactions to every truss).
The better option is to click on the add reactions button and then you can select the individual reactions that you are interested in showing.
This may also be helpful if the EOR needs to see reactions that they will be interested in.