Hi @netvilox
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Hi @netvilox and @triico
I think that the wpForo has created using RWD (Responsive Web Design) principles, so that, the contents of the Forum "adapts" to the size of the screen of the User's Device.
So it's not really a problem per se, because that is how it was designed to display. On a Desktop, it will display as "stretched", and then on smaller devices like tablets and mobile phones, it will "stack down" to fit the screen.
Plus, there is also the User's settings on their specific DEVICE being used to view the website.
For example, On my iPhone, if I use the "smallest font" (iPhone > Settings > Display & Brightness > Text Size)
The wpForo Community forum, would look like this to a User like me:
I mean I want the first picture attached to a topic to show under the title in the homepage.
Example.com/community
I think the wpForo Forum is not designed to work that way. What you want is a major customization that would require another entire Layout Design.
Here's information on wpForo's layouts: Simplified, Extended and Q & A Layout
https://wpforo.com/docs/root/forum-themes/theme-layouts/
And the Threaded Layout info is here:
https://wpforo.com/community/wpforo-announcements/wpforo-1-6-0-is-released/
I would suggest that you read and study the documentation and then when you have a better understanding of how this software works, then that would be the best time to customize anything, because doing that would minimize "New User" errors which can become challenging to troubleshoot at times.
Also the "Forum Search" box here is a great resource in learning the other "New User" or "Newbie" questions that have been asked and answered by the Support Team or other Community Members.
Good luck and God bless you!