Create random list of size "n" containing elements from another list

I want to create random string filled with "S" and "O". For example, my desired output is like:

SSOSOOSO
OSOOSSOS
SSSOOSSO
OSOSOSOO

With my code I change randomly every line, so what is the way to change every position?

import random

rows = 4
columns = 8
char_list = ['S', 'O']

for i in range(rows):
    print(random.choice(char_list) * columns)

My current output:

SSSSSSSS
SSSSSSSS
OOOOOOOO
SSSSSSSS