Since https://github.com/lightningnetwork/lnd/pull/506, `defaultchanconfs` is nested under `bitcoin`. Using this parameter at the top level generates a warning message:
```
2018-03-17 23:07:08.273 [WRN] LTND: /home/bitcoin/.lnd/lnd.conf:7: unknown option: defaultchanconfs
```
and using it nested under `bitcoin` does not.