For the last 3 sprints or so, I've observed our Product Owner suddenly shoving new stories -- stories not previously in the Product Backlog -- at the top of the Product Backlog.Because of this, the existing items in the backlog never get worked on.  New stories continuously take over the helm and make into our Sprint Backlog.My question is - how much can the Product Owner really shake up the Product Backlog?  Is it really fair game to ignore what's already in the backlog and keep on shoving new stories at the top?I've tried to argue that this is hogwash, but I often hear counter-arguments such as adapting to frequently changing business needs, we're moving so fast - we're super agile and I don't know what to say to those arguments, although I feel it is not how Scrum was meant to be.EDIT:I understand that the product owner owns the product backlog.  What I am observing at my team though, is that the PO constantly puts new items at the top of the backlog, ignoring the existing backlog items completely.For instance, say we're building a car and PO creates 10 stories to make it happen.  We decide to take on 3 stories in our sprint backlog - thus 7 stories still remain in the product backlog.  Everything is good so far.At the next sprint planning, however, the PO now claims that we need to build a baseball bat and creates 5 stories around that - which are then placed at the top of our backlog (i.e. highest priority); nevermind those car stories we already had in the backlog.
Scrum: How much can the Product Owner shake up the Product Backlog?
scrum
It sounds like the PO is just doing their job. It is their job to know the needs of the customer, and to balance those with the needs of the business. They are the ones that decide what the company will ultimately sell. If they switch from automobiles to baseball bats, presumably that's because they've decided bats are more important. If they are more important, why do you want to continue to build an automobile?If the team is bothered by this, talk to the PO and tell them your concerns. Again, they are just doing their job, but they should know the effect this churn has on the development team. It's hard to focus on a product when you're constantly switching products back and forth.