Wait! What if it was permanent? Then what would be the point of all of this then? If he couldn't remember the now, how could he appreciate the new? What if the new was worse than how his life is now? At least now he had power to change things if he disliked them, if he was a human horse, then he would be powerless!
All of these thoughts raced into Jeffs mind the second he hit the start button. In a last minute panic, he tired furiously to make corrections. The program wasn't stopping though. He watched the loading bar slowly climb, 30%. 31%. 32%. Even though it wasn't instant, it was going quick enough where in less than 5 minutes, the program would begin. In his panic, he somehow managed to press the correct key to bring up the change list and was somehow still allowed to edit some minor things.
One of which was helis personal memory, which he quickly switched over from "replace entirely" to "preserve old and integrate new". The other big change he made was that if he was going to be stuck as essentially an animal, he wanted to at least enjoy it. Under the female tab, he changed female humans to be of low fertility, needing either numerous mates and/or constant sex in order to have a chance to successfully conceive an offspring. And instead of only once a year, human females could become pregnant up to 4 times, once every 3 months, and always have 2-4 offspring at a time, one of which is always guaranteed to be a female, while the rest are male. When a human female is in heat, unless she has a specific group of mates, she will welcome just about any partner, of either the human or horse species, as long as it is male and has a long enough penis to satisfy her and are not her own offspring. All female humans have at least 2 breasts, but depending on how many offspring they will produce durring pregnancy, some have 3 or even 4 total breasts to meet their demand. The last change Jeff managed to make was designating himself as still the owner and current user of the Chronivac in the new world, which would be adapted to allow for human use of course.
The moment he finished typing, the loading bar reached 100% and a blinding flash of light burst out from the device as everything went quiet and white before Jeff passed out.