First, convert the string into a list, replace an nth character and convert them back to a string. That’s a easiest way to replace an nth character in string Python.
Example replace an nth character in string Python
Simple example code.
def replace(s, index, c):
chars = list(s)
chars[index] = c
res = "".join(chars)
return res
print(replace("House", 2, "r"))
Output:

Do comment if you have any doubts and suggestions on this Python string topic.
Note: IDE: PyCharm 2021.3.3 (Community Edition)
Windows 10
Python 3.10.1
All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.

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