back tracking global alignment - Needleman Wunsch

the question is about finding all optimal global alignments between AAAG and ACG

I built the matrix for saving the score for each cell C(i, j) with match= 1, mismatch= -1 , and gap= -2.

the problem is how can I track back the score in order to obtain the alignments? I tried to save the direction from where the score came from in a new matrix, but I could not.