There is no setting to changes the Splunk's default chronological order of showing events (most recent to oldest). You can use "reverse" command to show events in opposite order.
I have found that the reverse command gives unexpected results, specially when there are a lot of events returned. Therefore, I use the sort command on the _time field.
<your search> | sort +_time
The only problem with sort is that it doesn't handle events with same timestamp well like reverse does. Otherwise if there won't be events with same timestamp or you don't care about the order in that case, sort _time can be used.