I think by "fixing the seed" they just meant using the "Reuse seed from last generation" button. By default, this will mean that all future images will get generated with the same seed, so they'll look identical. The "variation seed" thing mixes slight variations into this fixed seed, meaning that you're likely to get things that look similar, but not identical to the original. The "variation strength" slider controls how much impact from the variation seed is mixed into the original, with 0 being "everything from the initial seed", and 1 being "everything from the variation seed". I'm pretty sure that leaving the width/height sliders at their default positions is fine.
Also, just for future reference - lots of UI elements in A1111 have very descriptive tooltips, they help a lot when I can't quite remember the full effects of each setting.
By default the random seed is different for each generation, so even if the prompt and every setting is the same you'll get vastly different images ( which is the expected outcome ).
When you set the seed to a fixed number you get the same image every time you generate if all other settings and the prompt are exactly the same.
So I start off with a pretty high CFG Scale to give it enough room to imagine things ( Refiner and Resize turned off )
Once I have a good base image, I'll send it to img2img and iterate some more one it.
Thanks for info. I don't use img2img except when i want to "AI" a picture, but this makes sense, as one of the steps. I usually just "run off"* dozens of images and pick the best one - but i don't do this for a living or anything, just to be able to "find" a picture of something in less than a minute.
Also, just for future reference - lots of UI elements in A1111 have very descriptive tooltips, they help a lot when I can't quite remember the full effects of each setting.