First, please note that there are opening line (the up middle line)and changing line.
1.Turn the original numbers(50, 25, 50) to the changing line (same way like you unlock )while the safe box is opened. 50* 4, 25*3, 50*2
2.Then, insert the changing key and turn a quarter to the left.
3. Set the new numbers (82, 60, 25) to the changing line ( same way as unlock).
80*4, 60*3, 25*2
4. Turn the changing key to the right and take out, then new number has been set.
5. Test new combination numbers for several times by unlocking way.