Claim entries and prevent open editing.
There should be an option to make people claim entries, and only be able to edit their claimed entry. Now, it seems as though it's just a completely open document where anyone can edit others' availability.
This is also my biggest pet peeve with meetifyr. Every time I schedule an event without fail my availability gets edited by someone else. I think this is likely due to people being unfamiliar with the app, or clicking someone else's dates to "see what happens."
Easy fix (without say identifying someone by their IP address and only letting them edit their own) would be to click "done" when entering times to lock in availability, then have to physically click "edit" to change the dates under a person
For me the biggest single problem with Meetifyr right now is that everyone can modify everyone else's availability. So for example, I set up a meeting poll and enter my own availability, then invite a friend. My friend can enter their own availability (good), but they can also modify my availability (bad). Given how easy it is to change availability, it is highly likely that they will change my availability by accident. This is especially true when using tablet, and smart phone browsers. In this case scrolling left to right through the date range is done by touching and dragging the grid. If you touch on a user's row, you change their availability as well as scrolling. This makes the product unusable for most users right now, which is a shame, as in many other ways it is so close to perfect.