Just checked and yes... see below.  I know it's being said it's my "theme" but have no issue with this anywhere else. All the videos show normal.

Please forget about the theme, we're currently talking about addon options.

I still don't see 100% value in your settings. Have you followed to my instruction? have you deleted all caches and done Ctrl+F5 after setting the width 100%?

When I post a raw youtube link and save it... this is what appears.

A small box about 300 wide and tall.

Hi tmrmarketing,

Have you ever checked the addon settings in Dashboard > Forums > Settings > Addons > Embeds admin page? Please try to set it 100% and let me know if it works:

https://wpforo.com/wp-content/uploads/2018/01/wpFOro-Embeds-Youtube-width-100-percent.png

Please make sure the second dropdown is set % not px.

When I post a raw youtube link and save it... this is what appears.

A small box about 300 wide and tall.

Yes i told you already. It is your theme.

A small box about 300 wide and tall.

When someone pastes a link from youtube into a post, it shows up as a small square box, maybe 300 wide. Anyway to adjust / change that?  Thanks

See the two last post here:

https://www.discovervenice.eu/community/venice-carnival/venice-carnival-2015/

Two ways for youtube that perfectly fit in any screen. I haven't done anything than pasting Youtube code (link the for first and embed for the second).

It is a THEME feature, how responsive it is. And how well is made.

I keep forgetting to click the SUBSCRIBE when posting here. Suggestion... make it clicked by default.

it is an OPTION in wpForo settings.