How to extract certain values in a table and do something - python

I have the following table (df):

ColA	ColB
A	Q1
B	A2
A	Y2
C	L1
B	R2

I would like to print an output such that it prints based on the column values, i.e., if it is A then it should print 'Q1 in A', if it is B then it should print 'A2 is present in B', if it is C then 'L1 exists in C'. What I tried so far?

for i in df:
    if 'A' in df['ColA']:
       print(df['ColB'], 'in A')
    if 'B' in df['ColA']:
       print(df['ColB'], 'is present in B')
    if 'C' in df['ColA']:
       print(df['ColB'], 'exists in C')

But I get the following error: ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all(). How do I solve it?

Desired output:

Q1 in A
A2 is present in B
Y2 in A
L1 exists in C
A2 is present in B