replacing any value in a matrix

I have 3x7 matrix. I want to replace any number by 10 (which is greater than 4). I write this code but its not working. Can any body help me ?

A=[1,2,5,2,3,4,2; 4,2,1,5,3,2,3; 1,4,2,3,2,2,1];
%      1     2     5     2     3     4     2
%      4     2     1     5     3     2     3
%      1     4     2     3     2     2     1
for k=1:1:3
   if A(k,4)>4
       A(k,4)==10
   end
end

expected result:

% 1 2 5 2 3 4 2

% 4 2 1 10 3 2 3

% 1 4 2 3 2 2 1

[Walter Roberson]

A(k,4)==10

That is a comparison, not an assignment. Assignment uses =

Answer 1

[Walter Roberson]

A(A>4) = 10;

No loop needed.

[Muhammad Haziq]

Thanks