When creating an account, the system will automatically generate a default layout, which is the same as the one for invoices. If you want to add a signature block to your quotes but not to your invoices, it is best to create a new layout.
Go to 'Layouts' and click the red 'Create' button. Choose a new layout and rename it, for example, to 'Quote.' Then click 'Create layout.'
A new layout will now be generated where you can further customize your logo, etc.
For more information on designing the layout, please refer to this help article: Layouts
Scroll down until you see 'signature block' and check this box.
When you go to the print preview, you will see that the signature block has been added.
Press update layout to save all changes.
You will see that two layouts have now been created.
If you wish to use the "quotes" layout for the quotes, press actions > options.
And select where you want to use this layout. Then, press update.
When creating a new quote, you will see that the system now automatically uses the 'quotes' layout. (If you want to select a different template, you can do so under 'options' > 'layout'.)
Check if everything is correct by going to the print preview and see the proper mention of 'quote' appear there.