Just some tips and tricks in no particular order. I just added anything I could think of or was told of. Browse them and perhaps you'll find something useful.
You can click and drag (ctrl+click) to move the subtitles vertically. On mobile, you may touch and drag instead.
One pretty hidden feature is that you can paste an image in the mining editor dialog if you have it in your clipboard. Click anywhere in the dialog and Ctrl+V. On mobile, the trick also works, but because there's no physical keyboard, you'll have to be inside a text field, like the translation one, for example, and paste the image there. This should work.
So, officially there's no such button. But you can re-import as unknown all your words. Here's how you can do it:
There's no undo button, so be careful.
While I personally never use this, I want to point out that this exists. Before, you'd see all underlines by holding shift. Today, the keyboard command is pressing shift three times in quick succession. It acts as a toggle, so to revert you have to press shift thrice once more. If you want to keep this enabled at all times, you can do so in the settings.
Just thought it was worth mentioning to spend time exploring the settings; there's a lot of stuff, to the point there's a search bar.
There’s a setting to change the font for the reader and for subtitles. You might like the look better or find one that's easier to read.