The Sprint backlog is one of the artifacts in Scrum.
It has three elements you need to complete:
Let's talk about each of these elements:
The Why is represented in the Sprint Goal 🎯, and at the same time the sprint goal is the commitment for this Sprint Backlog.
The What are the product backlog items pulled ⬆️ into the sprint during the Sprint Planning by the developers 👨💻👩💻.
The How is the plan on how to deliver 📦 those product backlog items, and how to deliver the sprint goal?
And 'how', usually in practice, is represented by a bunch of tasks ✂️, so small work items that can be completed within a day or less.
Now the Sprint backlog is a living artifact, it should give you a real-time 📊 picture of what is going on and it's for the developers and just for the developers.
They need to self-manage their work and that means it will update, it will be updated 🔃 by the developers constantly.
So every day, there might come something new in 📥, something old might go📤, and something might be completed and marked as completed ✅.
So it is a living artifact, you can change it as much as you like as long ☝️ as you don't violate the Sprint Goal.
That is important, you can not violate 🛡️ the Sprint Goal.
And of course, if you want to change product backlog items, you need to negotiate that with the Product Owner 👩💼.
But apart from that, as the developers, you are free 🆓 to change whatever you like! 👍