Older Posts

There are two ways:
Note: If you choose the first option, test it on a dummy-site first to see how it works for you. It is not necessary to create a child theme, because this is only html and css, no php, nothing in it will cause a crash, if pasted correctly. Update issue: Just save the lines below, so you can use them again after an update (If the basic structure doesn´t change).

1st option: You create a new category as a parent of all of your current categories. Name it “Blog” or something like that. Then, go to home.php and put this between <!-- End Articles. --> and <?php endif; ?> :

<a href="http://www.yoursite.com/category/blog/page/3/" target="_self" style="text-decoration:none">
<div id="Oldones">
	<span style="color:white">
		<center>Older posts</center>
	</span>
</div>
</a>

Replace “yoursite.com” !
Set the number of articles shown in the slider to 3 in the slider section after “posts per page” ( near top of home.php ).
Be sure you have always set a post to “Featured”.
Have the homepage showing 10 posts for “newsfeed” in General Settings-> Reading (due to me using the german version of wordpress, I don´t know the exact terms of the interface) .
So, now you have 14 posts on the homepage, because of the “no duplicate” function.
That´s why the link above works with the 3rd page of your “Blog”-category.
You also have to set the number of posts on blog-pages to 7 (Settings -> reading).
Now the first two pages of archive-pages (including your parent-category) show each 7 posts on the first and second page, means the third page begins with the 15th post.

Also, put this into your Custom Css box in Leaf Options:

#Oldones {
	position: absolute;
	background: #444;
	color: #fff;
	padding: 6px 9px 5px 9px;
	padding: .6rem .9rem .5rem .9rem;
	text-decoration: none;
	width: 100px;
	width: 10.0rem;
	right: 20px;
	right: 2.0rem;
}

#Oldones:hover {
	color: #fff;
	background-color: #accentcolor;
}

Replace #accentcolor !
All that color-stuff will make that button look like the built-in pagination.
Now, when someone clicks that “Older posts”-button, that person will get to page 3 of all of your posts and the built-in pagination will display. But, if you go to page 1 of that Archive, you won´t get to the homepage again.

Adding a Home-button on those pages:
Go to your archive.php .
Paste the following code between </div><!-- #content --> and </section><!-- #primary .site-content .<?php echo leaf_grid_width( 'content' ); ?> .columns -->:

<a href="http://www.yoursite.com" target="_self" style="text-decoration:none">
	<div id="homelink">
	<span style="color:white">
	<center>Home</center>
	</span>
	</div>
</a>

Again, replace “yoursite.com”!
Paste this into your Custom Css Box in Leaf Options:

#homelink {
	position: relative;
	background: #444;
	color: #fff;
	display: block;
	padding: 6px 9px 5px 9px;
	padding: .6rem .9rem .5rem .9rem;
	text-decoration: none;
	width: 100px;
	width: 10.0rem;
	left: 0;
	bottom: 8px;
	bottom: 0.8rem;
	z-index: 5000;
}

#homelink:hover {
	color: #fff;
	background-color: #accentcolor;
}

Again, replace “#accentcolor”!

And have a div around the pagination like this:
<div id="mypagination"><?php leaf_pagination(); ?></div>
You only have to add <div id="mypagination"> and </div>
<?php leaf_pagination(); ?> already exists!
Also paste this into that Custom Css Box:

#mypagination {
	position: relative;
	bottom: 30px;
	bottom: 3.0rem;
	z-index: 5000;
	right: -20px;
	right: -2.0rem;
}

This is a solution requiring a bit of mathematical understanding and effort, but comes along using solely html and css.

2nd Option:
This solution is way easier. But it won´t work perfectly.
Have a look at http://ww.wp.xz.cn/support/topic/pagination-issue-10?replies=3

In addition, Leaf theme has a child-theme ready, you have only to download it

This solution is way easier. But it won´t work perfectly.

For me works perfectly.
My doubt was only on the code writing, but it works.
But it’s for pagination (1,2,3…), not for “older-newer posts”