Why is my boss so condescending?

He is condescending, pessimistic, overbearing ***. I have been at this job. for a little over a week and I have had it. For starters there is a lot of info to know and they do not train you, its all learn as you go...we have to deal with the customers at the desk, the customers on the phone, the computer system and the millions of paperwork. When someone does try and teach you about something its to much for you to learn and remember everything they just tried to cram In your head. with this of a boss it is even worse he looks for every mistake you make and gives you a 15 minute lecture on what you did wrong he talks down to you and treats you like an ignorant child. I dread going to work when I know I have to work with him cause its so stressful like walking through a minefield. To give him credit he knows the job inside and out and he treats everyone at work the same way. They can accept that treatment but I cant. How do I deal with this type of boss until I can find another job? I feel like nothing I do is right and I am wary to even try because I know Im just going to be reprimanded for it later. What do I do?