第二个if语句中有一些额外的代码，第一个if语句中没有match incrementor，也不需要found变量，这段代码应该可以解决这个问题

# get input from the user
A = input('Enter string')
B = input('Enter string')

# set the incrementors to 0
i=0
match = 0

# loop through every character in the string.
# Note, you may want to check to ensure that A and B are the same lengths. 
while i<len(A):
    # if the current characters of A and B are the same advance the match incrementor
    if B[i] == A[I]:

        # This is the important change. In your code this line 
        # is outside the if statement, so it advances for every 
        # character that is checked not every character that passes.
        match = match + 1
    
    # Move to the next character
    i = i + 1

# Display the output to the user.
print(match, 'positions.')

num_matching = 0
a = "Hello"
b = "Yellow"

shortest_string = a if len(a) <= len(b) else b
longest_string = b if shortest_string == a else a

for idx, val in enumerate(shortest_string):
    if val == b[idx]:
        num_matching += 1
print(f"In {a} & {b} there are {num_matching} characters in the same position!")

根据@gog对zip和zip_longest的看法，我的答案可以简化：

string1 = "soon"
string2 = "moon"

matching_positions = 0
for c1, c2 in zip(string1, string2):
    if c1 == c2:
        matching_positions += 1
print(matching_positions)

输出：

3