I want to be able to call up an old invoice to create a new estimate from. To my knowledge, QB does not offer this capability.Does anyone know how this can be done?

Good morning, @myersbillboardse. 

It's great to see a new face here in the Community!

Yes, you're correct. You can only convert an invoice from an estimate, not an estimate from an invoice. 

I do recommend submitting your feedback to our Product Developers so they can consider adjusting this feature so that this action can be done in the near future. Here's how: 

1. Go to the Gear icon in the top right-hand corner. 
2. Press the Feedback option. 
3. Enter your suggestions. 
4. Tap Next to submit the feedback. 

Feel free to come back if you have any other questions or concerns. Have a wonderful day!