How to change the portrait in menu ?

Hello everyone, i'm trying to change the portrait displayed in the selection menu (before the game is launched). I already know how to change portrait in game by using trait in the character code (i mean where the character is defined), but those doesn't apply to the portrait in the main selection menu So I would like to know which place I should modify to have those changes reflected in the menu.

Any ideas ?  More specifically here is what I mean  :

As you can see Aerys's portrait is not displayed correctly.

So far what i did in terms of code was adding a trait carrying this new static portrait in the file history/characters/crownlands.txt

77037 = {
    name="Aerys" # AKA: Aerys II the Mad
    dynasty=496
    dna="cjjehgmdaaf"
    properties="aj0af0"

    martial = 3
    diplomacy = 5
    intrigue = 9
    stewardship = 10
    learning = 7

    religion="the_seven"
    culture="high_valyrian"

    #add_trait=quick #whose idea was this?
    add_trait=fair #handsome


    father=77036
    mother=77036496

    disallow_random_traits = yes
    #### gabMod ####
    add_trait = portrait20
    ###############
8243.6.1 = {
    birth="8243.6.1" #18 on ascension
        effect = {
      
        set_character_flag = potential_targ_lunatic
        add_character_modifier = {
                name = "abomination_of_incest"
            duration = -1
        }

        ....
}
}