In Power BI Desktop Query Editor, the Navigation step is to find the table you expect in data source. If you edit this step and select another table, this dataset will be changed into the table your selected (even the dataset name is still the previous one) so that all steps after that will be removed since the table itself is already changed. So if you need to view other table data, I suggest you create another dataset for that.
I have this problem as well. I have a query tied to Azure Data Lake with a csv in a file structure by year, month and date. I want to select a different folder and file that has the same structure. But when I try to change the navigation step, it erases all following steps. It does warn me of this, but it's frustrating to have to recreate the following steps.
Alternatively you can adjust the step in the Advanced Editor.
If you don't know how to change it, you can first create a duplicate query, adjust the navigation step (losing all next steps, but now you have the code you need to adjust the step in the Advanced Editor in the original query).
Yes! I had not checked there and sure enough, that should work. It was throwing me off that the formula bar only showed the last step of the navigation. But the Advanced Editor has all the steps.
Additionally, any chance you know how to have the navigation find the latest folder (the records are stored daily under a folder hiearchy that includes the year, month (number), and day. Any way to automate the navigation to always go to the latest date and get that file?