Potty issue

Hi

Our senior (12 1/2 y/o) Staffordshire terrier has started urinating inside our apartment complex

We got her at 9 years old from a shelter – she’s always been really good at potty outside until recently. She keeps going either outside of the lift or inside the lift. Note most of the time she’s not desperate to pee as she usually tells us when she’s ready to go – either vocally (she’s really vocal when she wants something) or she’s been trained with the buttons to let us know she wants to go outside.

There’s instances I accept where for example she’s scared of something outside like fireworks and has wee’d in the lift – which I’ve not been mad at her for . But the last couple of times it just feels like she’s being too lazy to wait to go down. Is there any way to train this to stop? So far we have just told her off in a stern voice so she knows it’s not acceptable

In terms of her health she does have arthritis, she’s on supplements which really help her joints (we’ve seen a massive difference where she’s gone from stiff legs and limping to back to normal pretty much), her walks are also limited to 20 mins as suggested by vet and she has a pram for longer walks

FYI we do have a balcony and have previously attempted to train her on fake grass but she refuses to go in the one spot, she always does a circle before she wees so have never been able to train her and I obviously don’t want her weeing down to our neighbours balcony so that’s not an option unfortunately

Many thanks for your help