Slow down render?

Hi, I’m new to these forums but have still been using blender for the past 4 years.
I have recently started learning to use the animation and rigging aspect and have got quite stuck:

I’m making a fake promotional advert for a non-existent arcade game (for a design project). I made all the necessary assets, rigged them all and did a few test renders - everything working fine.
so I decided to go ahead and render the whole thing. this is where the problem came; I found that for some of the scenes my text boxes that hold information such as character movement and the like move in and out of shot too quickly (and thus are impossible to read) however, these are directly related to the far more complex background so simply re-making the keyframes for the text boxes is not an option.

I need a way of slowing the speed of the animation whilst still maintaining a solid 24fps (to avoid any sort of horrible jumpyness) re-keying all the keyframes for the scene would take hours so ideally I need something quick.

I searched around Google to no avail so decided coming here to ask for help would probably be a better idea.

Thanks in advance

Jo