Why does this list element move back in the list?

For context, what I am trying to do is create a top-down display in which the screen is just text which is printed every time the player gives input. What this script does is move the Y upward so that I can find things I could do to move the player when the input is given.

minimap=[
        'HHHHHHHHHHHHHHHHHHHH',
        'H                  H',
        'H                  H',
        'H           HHHHHHHH',
        'H                  H',
        'HHHHHHHH           H',
        'H                  H',
        'H          Y       H',
        'HHHHHHHHHHHHHHHHHHHH']
for li in minimap:
    print(li)
count=0
for b in minimap:
    count+=1
    if count==7:
        soi=b
    elif count==8:
        s2i=b
minimap.pop(7)
minimap.pop(6)
list(soi).pop(11)
list(s2i).pop(11)
list(soi).insert(11,' ')
list(s2i).insert(11,'Y')
minimap.insert(7,soi)
minimap.insert(6,s2i)
for li in minimap:
    print(li)

So what happens in the two lines

minimap.insert(7,soi)
minimap.insert(6,s2i)

Is that the new, changed lines are inserted into the minimap[] positions of the old lines, which were removed from minimap[] (I say this because I believe it is most relevant to the issue).

However this is what happens:

HHHHHHHHHHHHHHHHHHHH
H                  H
H                  H
H           HHHHHHHH
H                  H
HHHHHHHH           H
H                  H
H          Y       H
HHHHHHHHHHHHHHHHHHHH

(New minimap:)

HHHHHHHHHHHHHHHHHHHH
H                  H
H                  H
H           HHHHHHHH
H                  H
HHHHHHHH           H
H          Y       H
HHHHHHHHHHHHHHHHHHHH
H                  H

Everything worked as expected, however, (it seems that) line 8 and (new) line 7 swapped positions. Why did this happen?

minimap.insert(7,soi)

minimap.insert(6,soi)
minimap.insert(6,s2i)

minimap.insert(6,s2i)
minimap.insert(7,soi)