It sounds like you are using the wrong tracks for video and effects.
The top track, #1 should have your main video media.
Everything you want on top of that, like text, must be placed below. Place the bubble on a video track below and it will show on top of your video.
Then you place your text below the bubble so the text will be on top of the bubble.
It's just layers, like looking up from below, you see the text, then the bubble, then the video.
Hope this is what you are needing.
Richard
PD10, build 10.0.1129b SR VDE111213-07
Windows 7, 64-bit, Intel Quad core 3.3 GHz, 4 GB RAM, Intel on board graphics display (shares the RAM), 931 GB free space