[Cropping and Resizing]

Long-time PS user, new to Affinity Photo. Mostly like what I see so far. BUT, I am having a problem. I don't do a lot of 'graphic' design work but do a lot of cropping and resizing of user supplied images. Nothing elaborate, just very basic. Scenario goes like this...

1. User uploads image to my website. (I then download to my local computer)
2. Image loaded into Affinity Photo
3. Remove un-needed areas around the photo edges via Crop tool.
4. Resize the document/canvas to add border around photo.

BUT, if I resize the document the cropped area expands to the new size requested. If I resize the canvas, the original canvas (before crop) is shown but with the desired 'border' around it.

Surely I am missing something, but what?

 

TIA for any assistance

jdadwilson