I'm sorry for the problem you have, but unfortunately what you experience is a desired behavior.
Here is how it works - when changing a name of a coded step class we don't know if this is a new coded step or edit of existing one, so we place the coded step in the steps sequence bellow the marker in Test Explorer for where the next recorded step to be. In your case the marker has been at the bottom of the test and when editing all coded steps, they were all put at the bottom.
In this case, what you want to do - edit all coded steps at the same time will not preserve the test steps sequence. You will have to do the renaming of the coded steps one by one, making sure the cursor for record next step is above the currently edited coded step in order not to have your test rearranged.
I'm sorry for the inconvenience and not being able to offer you another solution, but hope this guide will help you in not ruining your tests in such scenarios.
the Telerik team
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