A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Hi Aidankraus,
I agree it’s easy to add the trendline to the chart in the Excel but since you mentioned you can’t see the + symbol beside the chart, we would like you to try the below steps and check the outcome:
Open the Excel file with scatter chart> Click on the Chart> Chart Design in the Ribbon> Add Chart Element in the Chart Layouts sections> Trendline.
If you cannot see the Add Chart Element in the Chart Design tab, please try to remove the chart inserted and re-insert the chart to check the outcome.
Please share us the updates after giving a try and we will keep assisting you further on the concern you are facing.
Best Regards,
Chitrahaas