How do I change company start date from Jan 01/2020 to Jan 01 2021?

Hi there, 

QuickBooks Online makes it easy to navigate and I'll be happy to show you how to change the fiscal year date on your account. Sometimes it's necessary to change the date and in order for you to do this, click on the Gear icon > Account and Settings > Advanced > look under the Accounting tab > change the fiscal year. 

I encourage you to give this a try and if you have other questions, don't hesitate to reach back to me in the comments below. I'm here to help.