Spacebar and other keys working weirdly.

For the past year if not more some of the keyboard keys that I've been using has been working weirdly. I don't know if this has anything to do with the fact that I use a Compaq keyboard instead of a Mac keyboard. Years ago my right ctrl key has for some reason now affects the volume on my Mac. It did not do that before and now I basically had to partially detatch the key so I don't affect the volume by mistake. Most recently my spacebar and my arrow keys started functioning different when it comes to the QuickTime player and on YouTube. Originally the spacebar only play/paused videos. Now if I change YouTube's speed, quality, autoplay, or even the closed captioning settings, pressing the spacebar now acts as a "last used button". Using the spacebar will no longer play/pause, but instead will highlight the last setting used and affect that instead. I'll have to click with the mouse on the video to play/pause so that the spacebar can play/pause the video. This also affects my QuickTime player whenever I need to trim a video. Originally I could trim the video I need and using the spacebar will play it. Nowadays it no longer works and the trim tool is permanently highlighted in blue. Something similar happens when I use the directional arrows whenever I want to skip a YouTube video in 5 second increments or change the volume. Instead of skipping or rewinding in 5 second increments, the right and left arrows will instead increase or decrease the volumes when already the up and down arrows affect the YouTube player's volume. Has anybody else experienced this issue? Included is a picture of this highlighting phenomenon when I'm using QuickTime's trim function. The left side of the trim bar will be affected but not the right. And that highlight seems to prevent me from using the spacebar to play or pause a video when editing.