Two. First is that you can't directly add an image to the forum. You'll either need to save the screenshot and then upload it using the attachments button:
Or upload the image to a photo sharing site like Imgur, and then either have it generate the BBC code and place it in the text box directly, or paste the pic's URL into the forum's inline image tool:
For your main question, I see all effects in play when I adjust them, however the shadow effect is
very subtle and you really need to zoom in to notice.
In this magnified example, the top line has no shadow, then black and yellow:
Since there's no adjustment for intensity/thickness of the shadow and border options, your best bet is to go with a solid contrast between the text and border colors, maybe with the shadow matching the text ensure that the border will stand out on its own if the video background is close to the text & shadow color.
If you can follow the first part of my response and attach your original screenshot, maybe we can find better visibility options for your specific project.
YouTube/optodata
DS365 | Win11 Pro | Ryzen 9 3950X | RTX 4070 Ti | 32GB RAM | 10TB SSDs | 5K+4K HDR monitors
Canon Vixia GX10 (4K 60p) | HF G30 (HD 60p) | Yi Action+ 4K | 360Fly 4K 360°