Q.Watermelon Is Soft All Around, Not Blossom End Rot Though
In just the past 3 days all my watermelons that are not yet ripe are still very dark green and round, have all started to turn soft all around the rind of the melon. No brown spots or blossom rot. When I picked one to see if it was too ripe the inside was still white with some red meat, but soft meat inside also. Any help would be greatly appreciated. Lorraine

Certified GKH Gardening Expert
This has two main causes. Overripeness, and heat and direct sun, will be the primary causes for soft melons.Be sure that the fruit remains shaded by leaves, and be sure not to prune leaves, causing sunburn and scald to the fruit.
In some instances, this can be caused by uneven watering, as well, like letting it dry out too far and then watering too much in compensation.
This article will help you to grow watermelon to its potential:
https://www.gardeningknowhow.com/edible/fruits/watermelon/growing-watermelon.htm