is there a way to make a for loop going through a table start at the same row after it switches columns?

Whenever this code runs it replaces values the way it should, but every time it moves over 1 column, it goes down 1 position in a row.

the results look like this

X B C   
X Z C
X Z Y
A Z Y
A B Y

when they should look like 

X Z Y   
X Z Y
X Z Y
A B C
A B C

[Steven Lord]

Please show "this code" that you run that demonstrates this behavior as well as a segment of code that creates a SMALL sample table on which to run "this code".