1. Use Notepad (Windows) or TextEdit (Mac), as these are text editors and not word processors. Word will try to interpret what you have typed into what it thinks you meant, and it will mess it up.
1a. It looks like the app “Textor” is the best equivalent for iOS. It's free.
2. Use Courier New as the font. Or if you must be a rebel (Looking at you, Jay!), Lucida Console (Win) or Monaco (Mac). They are monospace fonts - each character has the same width. So when you line things up vertically they stay lined up. (It looks like Textor handles that for you, nothing to set there)
3. If you choose not to follow 1 and 2, then before posting on BBT paste your tab into Notepad or TextEdit and see why 1 and 2 are 1 and 2.
4. Don't try to edit your tab on BBT - go back to 1 and 2. You can edit on BBT, but there's a good chance you'll mess it up. Just do it right. You did save your tab, right? Save is on the CTRL-S in Notepad, Command-S in TextEdit.
5. Keep lines below about 90 characters - BBT will shrink the display font if you don't, making your tab very hard to read. This includes making sure you don't have any extraneous stuff out past the ends of the lines as well - a bunch of extra spaces will do it, even though you don't see them. It's the one thing you can fix in a posted tab pretty easily. 4x 16th note measures, 5 measures breaks, a set of repeats and the string names is 72 (73 if drop tuned), so keeping text lines the same length means you're in good shape.
Marko - if you have the line of text outside the
tags in your forum post it will format correctly. Or figure about where it should break and add an “Enter” yourself. Submitting a tab has everything between those markers, hence #5 above is important to remember. If you edit your post and copy the “Just used…” line below the tag it will format correctly.
As to your tab itself, you have a different number of characters on each line, hence the end of line marks ( | ) aren't aligned. That's 1 and 2.
Just like playing bass, no one gets it right to start. You have to work at it. My career has had me doing enough coding that I knew what would happen with the formatting before I posted my first tab, so I was on top of it, but I still had to tweak things a bit to get it how I wanted it to look. Copying one of Lon's tabs to get the formatting helped a lot, too.