change letter in a string python code example

Example 1: python replace letters in string

my_text = 'Aello world'
my_text = my_text.replace(my_text[0], 'H')
print (my_text)

Example 2: python change character in string

mytext = 'Hello Zorld'
mytext = mytext.replace('Z', 'W')
print mytext,