I have a question - I deposited some clam into my wallet. a few months later, I sent that balance to another address and it said the transaction came from a new address. how is this possible? does my wallet have multiple addresses, or does it change the address regularly? I had one address a few months ago, and now I have a different one. Confusing.
When coins are received, they are received in a single 'output' at the address they were sent to.
That 'output' is a single unit.
When you make a transaction, every 'CLAM' of that output must be accounted for - not just the amount you are sending.
For this reason, even if you send a single 0.00000001 'clamoshi', the entire output must be spent.
So, the remainder, the 'extra', the 'change' is sent to a different address you control.
This is likely what happened in your situation.
Receive 10 CLAM at address 'A'.
Send 1 CLAM to address 'X'.
The other 9 CLAM goes to address 'B', your change address (9 + 1 = 10).
Now, all your CLAM is at address 'B', a different address from the one they were sent, initially, to.
Send another 1 CLAM to address 'Z':
"Why did the CLAM come from address 'B', and not 'A'?"
Edit for clarity:
The entire 'output' doesn't actually have to be sent to an address, though I left this out to keep it simple.
Any amount not accounted for actually goes to fee.