Squeeky stairs
 

How do you fis squeeky stairs?
there is no access under them and the repiar needs to be cosmetically neat.
There does appear to be a gap between the step and the riser.

Any help is appreciated.

Only way I know is to countersink a screw hole to allow a screw or two to be driven through the tread into the stringer. You can install a plug to hide the screw.