Evolution supports the following global settings:
[] Keep signature above the original message on replying conflicts
[] Start typing at the bottom on replying

Those settings should be additionally configurable per account because they do not work the same with all reply styles.

Reply styles are configurable per account.
Top posting with signature above original message is applicable for 'Inline (Outlook)' reply styles but most often is not applicable for 'Quote' reply style.

So whoever has multiple account configured with different reply styles, it needs to manually cut+paste signature on every reply in account where the default doesn't apply (which is terrible for usability pov).