Quick answer: The create table statement is an editable text. In particular you can copy/paste it into a notepad (or any editor), change all to lowercase and copy/paste it back before to push the create button. (Useful also for non-standard SQL dialect, like Date/Time/Boolean types).
Neat answer: Edit the connection. On the right panel you have a
General/Advanced/Options/Pooling/Cluster menu. Go to the
Advanced panel. There you can tell weather your database is using uppercase or lowercase.
Stupid but quick use of the clever answer: Use the
Advanced menu to force quote around identifiers.
Really smart answer: Edit the MySQL connection and select the
Options menu, and refer to that page. Postgres conforms strictly to standand SQL, so be reluctant to change the
Options default for Postgres connections.