change background color in selected rectangle

[IrfanUserGuyxyx]

What happens when you click and drag a selection area rectangle?

[oldtimer]

I cannot access "select" any more. I seem to be stuck in "crop". I do not want to crop anything, just to select an area of an image, which I was able to do a couple of days ago but no longer.

[IrfanUserGuyxyx]

In the color picker make sure the color you are replacing is in the background and the new color is in the forground, Notice in the screenshot below the selected area is the only area changed.

[Bhikkhu Pesala]

Try Colour Corrections (Shift+G). That works on the selected area.

[oldtimer]

I have a jpg with a clearly defined rectangular section containing black writing on a red background. The red is too dark, so the writing is hard to read. Another part of the jpg has the same dark red and a lighter version of the same color, which would solve the problem. I have gone through the procedure, with a sample of the original color and a sample of the lighter "new" color, but I am totally unable to change the color in the selected rectangle. Nothing happens. Am I missing a plug-in, ot doing something wrong?