Tuple by default? Lists inside of lists

Question

I created a small matrice with lists inside of lists but it's a tuple by default, why is this?

Answer 1

That doesn't happen.
Can you show us the code?

Answer 2

Also if you have a tuple, you can make it a list by list()
t = (1,2,3)
t = list(t)
print(t)
[1,2,3]