Thank you for the post.
Did this used to work in previous versions of FileMaker Go 12? Other iOS applications (including the iOS camera app) do default to the last choice, so that behavior is possible; however, if this always worked this way, then the behavior may be as designed.
I do agree this would be a convenient feature to have, so I forwarded your report to Development and Testing for review.
Additionally, if you would like to see a change in this behavior, I would encourage you to enter this as a suggestion into our Feature Requests web form at:
These web form suggestions are monitored and read by our Development and Product Management departments and then discussed and considered for a future release. Although I could copy your post and paste it into the web form, there are some questions asked that only you can answer.