My website layout is not viewable in the same format on different devices.

[HPIAccounting]

Whenever I try to view the website in the different formats of (mobile, desktop, and full screen) it all looks different. I cannot figure out how to make everything streamlined to look the same on any device. It cuts off part of my pages on mobile and the images don't fit on the page in full screen. I have tried to resize in the theme settings in layout but cannot figure it out for the life of me.

[HPIAccounting]

Is there a charge for this service or is this part of the shopify support?