Here's a quick little tutorial on how to change some forum settings around to your liking.

On the menu bar you will see a few icons which you are probably familiar with, but two that you might not be. If you click on the lightbulb it will change to light mode, if you are in light mode currently that icon will look like a half moon and switch you to dark mode.
To the left of that is a slider, if you click on that it brings up this:

Here you are able to choose which header image you want to see, the overall forum width (fluid width on will make it as wide as your monitor), whether you want to see the forums in a conventional list or a grid, whether you want the sidebar to be sticky or not, you can flip the sidebar so it displays on the left, and then you can either enable or disable the parrallax effect.
If you have any questions just reply here and I am happy to help.

On the menu bar you will see a few icons which you are probably familiar with, but two that you might not be. If you click on the lightbulb it will change to light mode, if you are in light mode currently that icon will look like a half moon and switch you to dark mode.
To the left of that is a slider, if you click on that it brings up this:

Here you are able to choose which header image you want to see, the overall forum width (fluid width on will make it as wide as your monitor), whether you want to see the forums in a conventional list or a grid, whether you want the sidebar to be sticky or not, you can flip the sidebar so it displays on the left, and then you can either enable or disable the parrallax effect.
If you have any questions just reply here and I am happy to help.