EDIT: Nevermind! I figured out what I was doing wrong. Thank you, though!
I'm using Affinity Photo. This is the scenario: I have an 14 x 9 inch (landscape) jpg of an advertisement that I need to edit to fit an 8.5 x 11 inch (portrait) page. I need to cut and paste parts of the ad around in order to do this. I created an 8.5 x 11 inch document. Next, I placed the image onto the document. Naturally, some of the image falls off the document. As an image layer, I am unable to select part of the image, cut it and paste it onto a new layer. What happens is the entire image gets pasted onto the new layer. So, I converted the image layer into a pixel layer. Now, I am able to select a portion, cut and paste into a new layer, but the rest of the image (the part that fell off the document bounds) has disappeared. It has been clipped to the canvas. Unclipping the canvas is pointless because although it now shows the entire image, it defeats the purpose of creating an 8.5 x 11 document in the first place. What am I doing wrong?
In Photoshop, I'm able to create a document of whatever size, place or drag in an image of any size, and manipulate the image as I need to and the parts that fall off the document bounds are still there.