Hi carrie37,
Welcome to Community! QuickBooks Online is a dynamic program with the features you need to complete your daily bookkeeping goals with peace of mind. Having the handy spell check tool isn't something that's within QuickBooks. However, I'd be happy to help you turn it on from your browser!
Here's how to turn on spell check for Google Chrome;
1. Click on the Three dots in the top right of your browser
2. Scroll down and select Settings
3. Click on Advanced > languages
4. Locate Spell check and turn it on
Here's a helpful guide for your reference.
Feel free to reach back out if you have any other questions. Your success is important and we're always pleased to help!