Unless there is a hidden property in the columns section I don't think there is a way from the table itself. It looks like you would need to set that at the tag level to not have so many decimals out.
I just took a peek at the docs Perspective - Alarm Journal Table | Ignition User Manual and I didn't see anything helpful. I loaded in and played with the table a little bit and couldn't find anything either. If you are storing the values this way, then you would want to see the value I suppose is the thought with no format option.
The workaround would be to use a normal table and populate it yourself from scripted alarm journal calls, then use cell render views to apply row-by-row formatting.