I'll provide additional steps to ensure you can find the single time activity option in QuickBooks Online (QBO), tclark.

We can verify that your user role has the necessary permissions to access time-tracking features. If you're not the Master Admin, check with the account owner to ensure you have appropriate access rights.

Here's how:

1. Click the Gear icon and select Manage Users.
2. Highlight the user's name, click Edit.
3. Under Edit user settings, go to User type.
4. Make sure to select the correct option to access and enter single time activity.
5. Hit Save.

I'm also sharing this article: User roles and access rights in QuickBooks Online.

Once done, let's check that time tracking is enabled in your QBO settings.

1. Go to the Gear icon and select Account and Settings. 
2. Choose Advanced from the left menu.

3. Select Time Tracking and confirm that the feature is turned on. 

However, if the issue persists, I suggest contacting our customer care team to have this investigated.

Here's how to reach them: 

1. Click the Help menu in the upper-right-hand corner.
2. Type in Talk to a human, then press Enter.
3. Select Contact Support Team.
4. Type again Talk to a human and click Contact Support Team.
5. Choose a way to connect with us.

I'm adding this article to learn more about entering a single timesheet in QBO: Enter a single time activity timesheet.

Please know that I'm just a reply away if you need any further assistance tracking a single timesheet. Have a good one.