I've got some info and steps so you can manage electronic signatures in QuickBooks Online (QBO).
As of the moment, the e-signature feature is not available in QBO but it is available in QuickBooks Desktop. As a workaround, you can manually affix your signature or integrate a third-party app that offers this feature.
Here’s how to integrate a third-party app:
Login to your QBO account.
Go to Apps from the menu tab.
Type in E-signature, then hit enter.
If you have found the app you're looking for, just click Get App Now.
With this, I recommend sending feedback directly to our engineers and may consider implementing them in future updates.