Video is just pixels. Always has been. If there something in a video that you want to change then you have to either mask it out then replace it or paint or copy some new pixels over the thing you want to replace. You can add a layer, change the color, or do anything else you want to the video that changes the pixels, but as soon as you render the video you just have pixels.
There are some video players that will allow you to add things like synchronized subtitles, but those kinds of things, including links, hotspots, and other interactivity are a function of the player and they have nothing to do with the rendered video. You have to use software that changes these elements in the player, but that has nothing to do with the original video.
It would be nice if video could be just opened and you could move things around or change the text, but video in its current form is just like a photograph. You can't edit it without changing the pixels because the only thing there is pixels.
To understand how this all works start here: How to add effects and motion graphics in After Effects | Adobe After Effects CC tutorials
What is the file format of the video? If I understand correctly, it is not an .aep? (After Effects file). If it is just a standard video format (.mov, .mp4 etc) it isn't an editable file format. If you are familiar with Photoshop, it is the equivalent of grabbing an image from the web that has text and thinking you can edit it in Photoshop. Once it's been exported to its final format (video for Ae or image for Ps) - then it is no longer editable. Make sense?
I once had a coworker show me video she had shot of her daughter kicking a soccer goal. Except there was another mom in front of her, blocking her view. She asked me, straight-faced, if I could edit out the other mom for her so she could see her daughter's shot. After all, she said, "It's digital."
You can, of course, create a new text layer on a solid and place that over the offending text.