What I did is I started to create a new report in Power BI Desktop. I connected it to the OneDrive Files that I needed for the report. Then I edited the query, right clicked the table, and clicked advanced editor. I then copied the source from this new report and pasted it as the source for the report that I had already created using local files. This let me change it to a OneDrive file, however, it is not an in-sync file like it should be when it is a OneDrive source because you have to create the report on Power BI Online. I haven't figured out what the source line would be for a datasource created in Power BI Online. If anyone else has a suggestion let me know.