Microsoft 365 & Co-pilot, getting started

Hi, my company has recently given me a co-pilot license to see how I can utilise this in Excel. I am trying to do some simple exercises to get familiar with the product. I have a small table of data and I am asking co-pilot to do basic things like add a total at the bottom, colour a cell green etc. Each time I give it an instruction, it is creating a new spreadsheet to download instead of giving me the option to 'apply' the change to existing worksheet. 

I have ensured that the autosave is turned on and I am on share drive. I'm not sure why this isn't working and wondered if anyone can help me with this issue?