I got a browser alert saying I used 84% of my data but when I went to check, I only used 4%.

Hi Riversong, the alert was dated September 5th, which was also the last day of your August usage cycle (08/06/18 - 09/05/18). When you log in to cox.com and access your Data Usage Meter, it will show your current usage cycle (09/06/18 - 10/05/18). To view last month's data usage, scroll down the page and click on the "Monthly" tab in the "Data Usage Over Time" section. This will display your data usage for the past 3 data usage cycles. -Becky, Cox Support Forums Moderator