You can change the settings in Mozilla Thunderbird so that you can automatically reply at the top of emails, along with any email signature, instead of at the bottom. Here are some simple instructions.

Set Thunderbird to start reply at the top of the email

1. Open the Mozilla Thunderbird email program.
2. Click 'Tools' in the top menu.
3. Click 'Account Settings...' from the drop-down menu.
4. Click the 'Composition & Addressing' option under the appropriate email account.
5. Make sure 'Automatically quote the original message when replying' is checked.
6. Selects the 'start my reply above the quote' from the drop-down option next to 'Then'.
7. For the 'and place my signature' drop-down option, select 'below my replay (above the quote)'.
8. Click the 'OK' button to save your changes.