If you have 3 transactions sent to a particular address, and you want to spend a very particular input, then you right click on the address that you want to send "from", click on 'send from', electrum will take you to the "send" tab, right click on the input that you do not wish to spend and click remove, and repeat as necessary (note: you can select multiple inputs to remove at one time if you wish).
One thing to note is that electrum will not spend inputs that it is not necessary to spend. For example, 18JqsJ9g4ybvxRHCLZAMgK1oUNGTon7g45 currently has two inputs, both of .9 btc....if I wanted to send .3 to address 1shorena... then electrum would create a transaction that spends one of the .9 btc inputs and sends .3 to 1shorena... and .6 to a change address (assuming 0 tx fee is paid). If I wanted to spend both inputs "in" the above address while sending .3 to 1shorena.., then I could create a transaction that sends .3 to 1shorena... and 1.5 to another address in my electrum wallet.
Great, thanks. I will have a closer look at it the next time I have some funds on my electrum wallet.