Over a year ago I loved editing slow motion videos using my S8 and S8+. I now have a Note 9. A year or so ago Samsung rolled out an update that crippled a loved and widely used feature across its camera line, including its flagship at the time, the Note 9. That feature related to editing slow motion videos. Previously, after taking a slow motion video you would be able to slide the triangles to designate which portion you wanted to be in slow motion. You could designate the entire video or just a tiny portion to be in slow motion. This was awesome for videos I took of my children because regardless if they were hitting a baseball, doing a science experiment, or whizzing by on a rollercoaster I could designate a tiny portion of the taken video to be displayed in slow motion. With Samsung's unfortunate update you can still designate which portions will be played in slow motion, but Samsung has, with zero explanation or even recognition, instituted a very significant minimum duration for the slow motion part of the video. This isn't a small tweak, the minimum is now upwards of 3-4 seconds, depending on the length of the video. Say your kid is hitting a baseball and you only want his swing to be in slow motion and then you want to see him sprint to first base in full speed. That is no longer possible because the Samsung video player software requires a minimum of ~3-4 seconds (of real time) for the slow motion part of the video. You can no longer slow down a .5 second snippet to see him swing and have the rest of the video at 1x speed. This change, that Samsung has never recognized or explained, has crippled the usefulness of slow motion videos. To be clear, I am not referring to the "super slow motion" mode in any way. I don't use that mode. If you want to see an example video of mine that is NO LONGER POSSIBLE see the link attached. This video is no longer possible. The longer the slow motion video taken, the longer the slow motion portion required as a minimum by Samsung (which if course makes no sense). Using my baseball example further, the Samsung update to the video player would require the entire pitch, the swing, and the run to first to all be in slow motion, because the software no longer allows smaller portions of the video to be designated to be displayed in slow motion. In other words, I can't pinch the slow motion triangles or balloons as close together as I want, and as close as I used to be able to. I don't want Samsung to develop something new just for me, I want to be able to edit slow motion videos like I used to, which gave me creative control. I have little creative control now and I hardly use slow motion videos because of how much Samsung crippled the software by establishing ridiculously long minimum times for the "slow motion" part of a slow motion video. This could be an easy fix for Samsung, perhaps a mistake was made and this was never intended to have changed... Please escalate this limitation that Samsung created, the slow motion editing software used to be perfect.
Try going to the galaxy store (something I try to never do) and updating your video editor. Search Samsung video editor if you need to find it. I was having the same issue (unable to make slow mo shorter than a certain minimum) and after updating the video editor this is fixed. I'm on a S10e and was super pissed about this flaw, and very happy to find a solution, so hope this works for you too.