The pick and pack app currently defaults to picking the most recent order. To change it you need to go in every time you use the app to adjust a filter.
The logical design would be from least recent to most recent. In a warehouse, you want to get the orders out that have been waiting for the longest first. You do not want to automatically pick the order that has just arrived. This is particularly true for working through large volumes and weekend orders. You want to get the order from Friday night out first on Monday morning. You do not want to leave the Friday order sitting there all day while picking the orders that come in on Monday morning. It is frustrating that we have to constantly update the filter as this should be the default setting.