Hi
I can try to help point you in the right direction on this.
Unfortunately, there is no setting to change that. There is a post where Barry helped someone get started on making a custom search field here:
https://tri.be/support/forums/topic/change-datepicker-in-map-view-to-display-months-rather-than-days/
That is about as close as we can get with the support on the forum.
It would as he said involve creating your own datepicker script as only the month view script uses the month datepicker.
Let me know if you have any follow up questions.
Thanks