Hey Lucas,
In the mobile app, the Default filter is normally the All Incidents / All Requests type of "All" filter. Basically its defaulted to an SDM Stored Query with symbol name: INASG
There's no easy way to change this from the app side.
However, if you change the stored query in SDM with symbol INASG, and have a different where clause which suits you. This way you are impacting the default filter on the app from the server side.
Hope this helps
_R