No! This isn't a naughtiness/housetraining issue, please don't tell her off.
The effects of spaying can happen at any time. I currently have two dogs, one a female, and she was spayed at around the same age as yours. By the time she was 6 she was having very intermittent nighttime incontinence, and now she's 11 she's a complete liability. She can only have limited treatments, which for us haven't proved 100% effective, so it's something we just live with (admittedly, I've never allowed dogs upstairs...I have working breed dogs and operate a strict pack here). Yes, it's a pain in the bum to clear up and live with, but she's elderly and can't help it at all.
6 isn't old for a staffie by any means, she's only about middle-aged. If she's only just started doing this since moving in with you, the chances are it's purely behavioural. Shouting at her for it will just reinforce the nervousness and you'll end up with a problem that spirals. You need to praise her tons each time you send her out for a wee - make a massive fuss - and just ignore any accidents in the house. If she's not really done this before the move, she'll settle in time. Make sure you spend time with her - don't fuss her when she's nervous as that will just tell her she was right to be nervous about something (dogs don't take comfort from that the way a kid does), but make sure she feels secure.
Impose some boundaries as the pack leader - it might not seem like it but having rules and routines actually makes a dog feel more secure. Remember they're pack animals - you're in charge and you determine everything. Some dogs can become incredibly nervous when they feel there isn't anyone in charge - in the wild a pack without a leader would be in serious trouble.
Does all that make sense or have I just waffled on? Feel free to PM me if you need any detailed advice. Dog psychology is a bit of a hobby of mine...when it comes to my cats though I'm as clueless as the next person