You have to go to the console tab and enter:
wallet.storage.put('gap_limit',100)
Then restart Electrum, you should now have 100 addresses in the receiving address list.
It will take longer to sync them when you start Electrum.
Awesome, thanks. I Did that and like 45 came up, but that is more than enough.
It takes a while, it'll eventually make 100, and it will automatically make a new one every time you receive bitcoins to one so that there will always be 100 unused addresses at any given time.
Just remember, if you ever have to restore from seed you might have to change the gap limit to 100 every time. As the gap limit just basically says "I'm gonna create addresses in order until i find 100 unused addresses then stop."
If you only have bitcoins on your 101st address, restoring seed will not generate that address witgout you putting in a gap limit of 101 etc.