YouTube keeps showing same videos on the home screen

1. If your URL contains any parameters then add &rel=0 at the end of it

   i.e., http://www.youtube.com/watch?v=joYtqNtZe6w&feature=plcp then add &rel=0

   so for example check at last

   http://www.youtube.com/watch?v=joYtdfdsNtZe6w&feature=plcp&rel=0

2. If your URL does not have any parameters then add ?rel=0 at the end of it

   i.e., http://www.youtube.com/embed/joYtqNtZe6w then add ?rel=0

   so

   http://www.youtube.com/embed/joYtqNtZe6w?rel=0

Note: This feature is not available from Sep-2018.

YouTube does automatically change the quality based on the player size by default, which means watching it in full screen will increase bandwidth usage.

If you want to stop YouTube from automatically changing it to a higher quality version, then log in to YouTube, go to Settings → Playback in your profile. Then choose "I have a slow connection. Never play higher-quality video."

Alternatively, if you only have a slow connection occasionally, then you can simply click the change quality button (the cog) and set it to a lower setting.

As long as the quality remains the same, then changing the player size will not effect bandwidth consumption.