Having problems with two of my dogs urinating indoors.  One is a 4yr old neutered male the other is recently neutered (as thought this would help) 2yr old male.  The problem is we also have a 17yr old very geriatric min pin! Bless her, who is prone to doing the odd little wee about the house, i think the other two have learnt to wee on top. Obviously when we are there this isn't so much of a problem, but if we are out sometimes can come home to several big puddles. I clean it up with a enzyme based cleaner from simple solutions. We do have hard floors which is a bonus but obviously would like to eliminate this. Any ideas please?

I would crate the boys, if out for short periods, or use a puppy pen for longer periods you are out, so that they are restricted to a smaller space and less inclined to soil where they will be sleeping and spending time.

The rest of the time vigilant supervision.

It could be they just can't wait, you don't say how long they are left and I have noted that because castrated dogs do not continually do a drop here and drop there they need to empty properly and the mechanism for six drops and cut off seems to disappear along with the testis so this may be the problem and perhaps a walk before you go out would help cure this.