We have QBO and have decided to change to QBO Plus. Can we run both programs on same PC while getting set up?

You may have more than one QBO account with the same email address on the same machine.

https://quickbooks.grsm.io/US

https://quickbooks.grsm.io/us-promo

Then you may run the first account on main browser, and the second one on incognito/private browser.  

@usloveladys 

If you have QuickBooks Online Essentials or Simple Start and need to upgrade to Plus plan, just go to Gear icon at the top and select Account & Settings under Your Company tab. Go the Billing & Subscription tab, you should see "upgrade your plan" link and proceed. It should be an easy process to change the plan.

Hope this helps!