[iMore Question]

basically long story short i went on my girlfriends phone the other day and went on the messenger app. she had no incriminating messages on her inbox, i clicked on the people option on the bottom of the screen and clicked on some boys name up the top. all of there convocations were in red lettering and his and hers chats weren't on her inbox but when i clicked on his name it came up with months worth of convocation i just want to know can you hide your inboxs on the app? also whats with the red type phase none of her other chats had it? and instead of saying 'messenger' or 'last online' it said thimble does anyone know what any of this means?
and yes i will be bringing it up with my girlfriend.