The custom trigger option gives you the ability to design your own custom trigger that fires up the accessibility toolbar. This helps to adjust the trigger location, look & feel based on your website design.
Don’t add a custom trigger in the footer.
Please add the link in the header and not in the footer.
Think of a keyboard-only user who doesn’t use the mouse. Such users have to keep pressing the TAB key at least 50 times to open the accessibility toolbar.
Plus, if he is a first-time visitor he will not have any clue about the presence of toolbar at all.
Hence add it in the header part. So that’s the first thing he/she will open when they visit your site.
Note: We auto-focus the link that acts as the custom trigger. Hence all your users will be scrolled to bottom automatically if you add the custom trigger in the footer.
To know how to build your own custom trigger, Click Here