Shon92

I currently am making an artwork for a gatefold album to be printed on cardboard. my artboards are perfect squares. i have them how i like them. but... i need to make the artboards 141 by 126 millimetres. How do i change the size of the art boards without stretching the first layer horizontally? i filled the artboards using the fill tool and imported images. i am really worried that i may have to start again to fit the templates. hopefully this is fixable. any advice would be much apreciated