Wow, that's a big variation!
Seeing as your analogue is so far off the other two, I'd guess that maybe it's faulty.
A few things to try
- weigh something with a known weight (try for 10kg or something, if it's only 1kg it will be too hard to tell)
- make sure you have it on a level, firm surface. Bathrooms often slope, carpet can cause inaccuracies.
- put new batteries in your digital scale.
Really though, scale weight is a pretty fluid number.
If you want to see if your weight is going down (or up!) then just pick one scale and use it in a consistent location at and the same time very day/week.
Remember that your hormones, monthly cycle, level of hydration, whether you've just been to the loo etc will all change the number on the scale and that doesn't necessarily mean that you've "gained or lost weight" in the bigger picture.
I think using clothes (how they fit) or a tape measure is often a better guide than the scales.