Hey,
here some tips: In the "Project bar" go right click on the project name, then "tools" -> "view project statistics". There check this sentence: "Estimated peak memory usage is..." For mobile games you should try to keep it around 150 MB or less. I don't recommend to go above that because then you will have especially older / cheaper phones / tablets which can't handle the memory usage.
If that's not the point in your case, here is another problem with images I had: Please check if you have any tiled-backgrounds which are very small (1x1px) and scaled up to fit the whole background or anything like that. This will let the game crash on specific phones / tablets (this has nothing to do with how good the phones are, but this error appeared only on some phones and there every time...).
Also check if you have any tiled-backgrounds which are completly transparent (so no image is shown, it's just a transparent file). This will also cause these crashes.