Images vanishing into page margins !

I appreciate this topic has cropped up a few times but, try as I might, I don’t really understand the answers provided !

I have left and right aligned images on some pages and when I view the pages, the images are only half visible as the other half has vanished into the borders and are outside the alignment of the text.

The net result is that the page looks a complete mess !

If I understand the previous explanations correctly, Twenty Fourteen does this to help make the page look good on a mobile. If so, that’s great but I can’t sacrifice how it looks on a desktop just to make it look okay on a mobile so will have to change themes if that is the case.

Can somebody clarify/explain or, better still, tell me how to align left/right images with text content ?