This is trickier.
MATS; instead of borders? Borders we know; attached to the print. Choose the color and thickness. One or two. End of story.
Mats are different. Instead of being a border, they are placemats under your print slightly larger so the edges protrude.
Advantages:
You can lay as many out as you wish making as many colors and sizes as you wish.
Any thickness you wish, including making some sides thicker or thinner.
You can edit the size and color of each mat easily, once you know the trick.
Disadvantages:
Not easy to move your prints around on a page (unless you know the trick.) Select the bottom or outside mat. Pull or drag that.
OK screen snap 063 shows us how to access mats.Right click on the image in the live view queue.
Screen snap 065 shows 3 mats, a red, a white, and a black, with the white one having a wider bottom side for text.
Also, if you look carefully, you can see a red dot upper right showing the selected mat. Every time, you click the print, a different layer is selected, hence a different mat.
066 shows the width of the 4 sides. Helper clue: if you type in a number like 0.10, and click any PLUS sign, all 4 sides will show the same. Then, you only have to redo the side you want to be different. (Changed the bottom side to 0.4.)
Snap 064 , if you look closely, is showing you a red dot in the upper right corner of the white mat, indicating that it is detected. Click on the image again, and the red dot moves to the next layer, etc etc.
Have fun and try it.
Fred