Strength & Noise
Strength allows the AI to change the image composition. Lower Strength will generate closer to the original.
Noise may allow the AI to generate more details but can cause strange artifacts if too high.
Note: Strength & Noise only apply when an image is used to generate with, so these settings do not appear in the menu unless that condition is met!
Play around with Strength & Noise
Goose Tip: If you use large sections with only one color you need to up the Noise setting accordingly to provide the AI with a working ground to create details from scratch.
Don't want to change much?
Lower both Strength and Noise down to zero, this should keep the image unaffected, this should regenerate your image unaffected. Now you may use Enhance or play around with other settings.
Goose Tip: Always keep in mind if the AI ignores your prompt too much, you may need to give it more room to work with - increase the Scale value of your generation!