In WordPress admin area post publish or update button is on the right top corner of the page. Though you can rearrange the tab but when the content of the post or page is too long then it would frustrate you when have to climb every time to update the post or page. Good news is you can easily update WordPress post or page from bottom screen by using a simple plugin Update from Bottom. This plugin shows two extra buttons (Top/Update) while you are scrolling down to the bottom of the screen.
Installation is very simple. Just get the plugin from above link and activate it. After activation try to update a post and you will see the button while scrolling to bottom:
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