Changing default images

[Moonmosaic008]

I have been looking for all over theme files where the images are set. i need to change default setting as they are not working correctly. For instance my cart image is showing 250x250 home default so i want to change it to medium default or on the product page instead of using large default I need to change it to  home default  etc. i don't want to resize them I just need my theme to pull the right image from the settings. it's affecting laptop and mobile versions. Where do i do this?

 

Thanks so much!

[Moonmosaic008]

Can anyone help with this please?

 

I have compared the default bootleg theme to my theme and even thought the preference/image settings (in this case large default) and all the others are the same the image sizes are different.

 

where do I set the image size back to 333x333 and not 458x458? 

I see that there is an added newbig_default image for products size 458x458so should I delete this or sizes it if I resize it then to what? 

Also when I add the item to the cart the image of the default bootleg theme is 166x166 but my theme shows 250x250. i need this image to be 166x166 so it fits correctly.