First I was playing in team Alpha, then i had to change team cuz Bravo didn't have much players. Then one of my team mates starts to shoot me and yelled "Why warheart is red"...what happened and how can i fix it?

Exit the game and rejoin.

Yeah it happen tp me to. Sorry i didnot use serch funtion but what is the problem??

This just happens occasionally because of packet loss. There's not much you can do about it except rejoining or making the person rejoin that seems to belong to the other team.

yeah it happens if you join or change teams just before/as/after the map changes