The checkbox for tracking original cost and depreciation is missing when creating a new fixed asset account. Is there a setting to turn this on or am I missing something?

Let me help you set up a new fixed asset account in QuickBooks Online (QBO), Christia-brostek.

We can create a new fixed asset account in the New Account panel to track depreciation over time. The checkbox for tracking original cost and depreciation is unavailable in the New account panel. If you need to calculate your asset’s depreciation, I'd suggest consulting your accountant who knows the best methods. You may also want to check the chart of accounts so you can better understand what each account is for and what it does.

Here's how to set up a new asset account: 

1. Go to the Gear icon on the top menu and select Chart of accounts.
2. Click New. Depending on your account view, you’ll either see a panel labeled New account or New category. Select the option you see below for the next steps.
3. From the Save account under ▼ dropdown, select Fixed Assets or Other Assets.
4. From the Tax form section ▼ dropdown, choose the option that closely describes the asset.
5. Enter a name in the Account name field.
6. In Starting date and opening balance, select a starting date and current value of your asset account balance field. If recording the loan, leave this blank.
7. When you're done, press Save.

After you set up your assets, we'll need to record their depreciation. QBO doesn't automatically depreciate fixed assets. Instead, you need to manually track depreciation using journal entries. For the steps and details, check out this article: Depreciate assets in QuickBooks Online. 

If you are using the QBO Advanced version, you can check out this article to manage fixed assets: Add and manage fixed assets in QuickBooks Online Advanced.

Know that our door is open 24/7 in case you need further assistance with this. You can also mention me in the comment section below. This way, I'll be notified and can help you right away. Take care always.