We would love to help out, but it's very difficult to answer your specific question without an example. If you upload a packaged workbook, we can then better answer your question.
How can I upload a packaged workbook?
Pie charts require a different setup than bar charts, and so using "Show Me" or otherwise trying to convert from one to the other will often not work.
You can upload a packaged workbook by replying, "Use Advanced Editor" in the top right corner, then "Attach" will appear in the bottom right corner. Use Superstore Sales if needed.
In the meantime, here's an old thread that once helped me create pie charts early on:
Under the File menu, click "Export Packaged Workbook..." to save the file. Then, when responding in a comment, click the "Use advanced editor" link in the top right of the grayed-out box. In the advanced editor, there will be an upload option at the bottom of the box.