'default to internal sim' - dont know what you mean, there is internal storage, or optionally your sd card. you cannot store applications (other than those 'tools' provided by your network provider) on a sim card.
It is odd and anoying that despite it looking in settings that you can default to internal sim to store apps - you can't. Instead they get installed in internal storage... This soon becomes full so there is nowhere for google store updates to go.
Took me 2 hours to figure the problem and move the apps:-(
By default this rom is configured to store to your external sd card.
Some users who have non Fat32 formatted sd cards see prompts about their sd card not being detected (but this can in fact be ignored and the card still mounts fine).