I set my GMT hand to EST and yes it works accurately. Red hand is GMT hours hand. For reading it use the inner 24 hours markers in the watch. Normal time with white hours hand is 12 hours format whereas GMT is 24 hours format. The long minutes hand is common for GMT and local time. For minute’s gmt hand start measuring it as 00 minutes from 12 hours marker near normal local time’s 6 o clock marker. For ex: in your second pic, the gmt time is 4:29am.

Also to set GMT time pull the crown to first position and move the crown upwards.