I believe what they complained is the number of pixel. You can check that in most to picture viewer. For example, open your jpg in Windows Paint, Choose Image -> Attributes, select Pixels. The Width and Height values are what you want to see.
To solve it, every time you new a picture, find the option to set your pixel or ppi (pixel per inch) to a proper value. For example, the default ppi is normally 72, you can set it to 360.