I don't think you can know which bread the post number is until you click it. Here's a tip. At the top right of the bread, click on Options. Under the General category, click Color IDs. Refresh the bread for the change to take effect. Now each ID will be highlighted in colors. If you're on a PC/Laptop, and hover your mouse over the "relied to" post number, the hover box will display the post, and if it's in a previous bread, the ID will not be in color.
This doesn't work on a mobile device.
What's helpful for me is to open it in a different tab. (Right click on PC, press and hold on mobile.
And back to original question of knowing which bread, there will be a description on the tab, or at the top of the bread.