Troube getting 3d fix for my bz 181 gps

hi guys! i recently built an quad with the bz 181 gps and speedy bee f405 V3 FC. i have been trying to get a 3d fix for my gps for a while now and it is not getting a fix. i have read many forums online and even tried changing setting like auto baud rate , and ublox type etc. how do i fix this?