Male dogs use urine as an "ownership" tool. That said this little guy needs a fair bit of your time to get him out of this entrenched behaviour. If it is fear doing it, scolding is not a great idea, but this is what I did for my chi x (he was rescued and supposed to be about 4).
He would lift his leg constantly inside, so I put a lot of time into training him out of it:
1. Get him sterilised.
2. Establish no bladder probs with a vet trip.
3. Every time you catch him at it...."No...that's bad" and
clean the area straight away (steam or a solution of
cheap white vinegar and water, followed up by a few
drops of citrus oil (dogs hate citrus).
4. Supervised trips outside, every time he lifts his leg in
an appropriate spot use a pee word and lavish him with
praise.
This requires a big effort on your part, and he will eventually get it. My little dog is very good inside now, it just takes time, love and patience.
Oh, the vinegar and water solution neutralises all kinds of urine (people and pets), so is handy in quite a few situations.