Much of the issues described is simply learning how to use the forum.
There are several very ways to navigate threads. On a computer on the right-hand side of your screen, you will see a scroll bar.
On the scroll bar in the image above if you can click on “6 Sep” to go to first post. Or “35m ago” to go to last post. These are buttons.
The scroll bar is also intelligent, move the bar and the date and number of the post changes. This makes it easy to navigate backward and forwards. (In image above the “111/113 14 Sep” is a dragable button, by holding down mouse button)
Alternatively use keyboard shortcuts
If you are on mobile bottom right corner is a post number eg 98/13.
This is also a clickable button.
If you click on this just like on the desktop you get a scrollable button (even with a preview of the post- see below).
The date numbers for first and last post are clickable buttons.
You also have the option, of using the “Jump To” button. This allows you to instantly jump to any post number, by for example type “1”