Player Size Not Changing/Adapting

Hello, as the title suggests; I am having an issue with not being able to change the player size. I tinkered and experimented with both my container options per my themes post settings and I also tested several things I saw and read through here and this forum; such as ticking and unticking the ‘always use fixed player size’, and all the same, I tried throwing several different numbers out here in both pixels and percentages but seemingly, nothing changed or affected the size of the player at all.

I’m just simply trying to get the player to stretch the full-width of the post container but can’t accomplish it; for whatever reason. Any suggestions?