Cheat Engine

[Bontoo]

Hi everyone.
I would like to ask some help here as im very new with cheat engine.
There is an app game on window 8.1 pc that im trying to change some value of some items.
Example coins. I tried to search with the exact value on 4 bytes. Absolytly no result.
Then i watched some training videos on youtube and i changed the searching procedure.
I found out that the game doesnt strore the exact value in the memory so i followed the steps below:
-1: Value type:all
-2: Unknown initial value
this found millions of results. then:
-3: I was keep changing between "unchanged value, increased value, decreased value."
-4: When i had like only 10 - 20 results left i tried to picked out the result from 2,4,8 bytes
Then i found 1 address was showned 3 times(same address) but with all kind of bytes 2,4,8 as well. all of them were different numbers(different long as well)
-5: Anyway i tried to change the amount of the coin in the game see how react the CE. Suprisly all the results changed with the same amount. But i changed in the game with 1 and in the CE changed with 40. all of them. I was quite happy to found the address so i calculated if i would change the value with 400 that should change the value in the game with 10. So i did and it was working.
-6: The problem starts now cos when i returned back to the game and collected any more coin, the game crashed right away and restarted.

I tried to change the debugger option in the extras but same result.
So now i can change a value in the game but after i changed it crashes.
Please someone help me with this. Anyway as i mentioned im new with this but i gonna keep looking for solution in the tutorials.
By the way the game names is World at arms.
Thank you!!
Krisz