There are a number of possibilities.
The most likely scenario is that you are working on the “Team Workspace” where everyone can move things. In this case it is possible that after making your adjustments, someone else moved the notes. To ensure that you have a workspace laid out to your requirements only, check that you are viewing your personal workspace (via the drop-down above the workspace on the right-hand side).
If you are observing a Sprint (and not able to add content), you can layout a workspace whilst you are viewing it but the changes will not be stored.
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