Try setting the default view for the advanced find to one with the Match case clear. To do this go to Tools>System>Presntation>Search>item type and set "View for find results" is a view which has Match case clear.
you can look ta setting the default view as Ruth mentioned. it would also be adviseable to remove the check for all views. This is a tedious task (speaking from expreience) but ensures that no issues arise out of Match Case being set to yes as default.