You will need to stain over the lighter one with something with red- maybe chestnut? ‘Red oak’ encompasses several varieties of tree.

I agree you need to find another stain for the risers, to match the treads. It sounds like you have used an all in one stain and poly together, and a better thing, would have been to stain all the treads and risers with just stain, and then when you had them all matching, and the stain was dry, then use a good quality poly on them all. At least 2-3 coats of poly. You will most likely have to sand the varathane off before restaining.

You probably need to stir it a little better. Get all the pigments in the can mixed in. Don't forget the bottom of the can. Shaking the can will not mix the pigments in.

It wasn’t an all in one stain and neither have poly yet

That is a good thing, that it doesnt have poly yet. You might try adding extra coats of the stain you are using, and hope you can get the risers to match the treads.