If your taskbar is displayed in full-screen mode, right-click on the taskbar icon (application, network status, volume, etc.). Still depending on that Flash abomination in 2016 would be morbidly depressing. Some quick fixes related to the taskbar displaying in full-screen mode have been reported. Ideally, these three services would just get with the times and use HTML5. Any platform that lacks Flash should stay that way, as far as I'm concerned. So for users to watch HBO, Showtime, or Hulu on SteamOS will require either special apps, or Valve integrating the horrible Flash-with-DRM needed by them, which I really hope they don't do.
I've heard of workarounds that involve installing depracated software, and these services do work through Pipelight on Linux (in fact they work better there than they do on my high-end Windows machine, which stutters occasionally during playback). These three services all use Flash (which is supported on Linux via Chrome but not in Steam BPM), but for some reason the video just loads forever on desktop Linux since it doesn't have whatever low-level magic DRM-sauce is required. Unfortunately, Hulu no longer works on desktop Linux because they recently implemented the same awful DRM used by HBO Go/Now and Showtime. I just can't fullscreen it because the button doesn't appear. And to clarify, while on SteamOS, the video does play, and I can pause it. So it works on desktop Linux now in Chrome, just like Netflix. Just beware by doing this, you may have difficulty resetting your display back to a readable format, so take caution before randomly inputting numbers.Actually, Amazon Prime Video recently switched to the same DRMed HTML5-based technology used by Netflix. This process will increase or decrease text and image size on both screens, which is only practical if you need a detailed view of something.
If you require a more precise display scale, you can use the advanced scaling option. Note that you may not get an exact fit due to the scale restrictions. If not satisfied, repeat the Scale and layout option above until you get the view you need. Be sure to slide it over all the way (or super close), or it won’t change the scaling.
Here’s how to adjust the scaling on multiple monitors to match up better, proportionally speaking. Even though Windows auto-adjusts the scale to make text and windows larger on the HDTV, you may need to tweak it because sliding windows to a different screen may alter its size, which is not always beneficial.
When you use multiple monitors and extend your screen, the scaling may be different, such as a default 1080P screen and a 4K HDTV.
Using Windows 10 Display Scaling for Two or More Monitors
How to Use Windows 10 Scaling on One Screen