Where can I change the default character set of a table in MySQL Workbench's data modeling tool?

You can set the used charset/collation combination in the table editor. You have to expand the header (which is by default collapsed to save space) to be able to change it. See this screenshot:

Thanks a lot for this topic : it saves me a lot of time (I searched the header that was just collapsed by default).

I just want to say that you can specify for the table collation the option : schema default (the first option in the collation drop list).

And then, you can specify too the collation for the text type fields : table default.

With that, you can control the collation of your database with just the global schema collation parameter.

(my mysql workbench version : 6.1.7 revision 11891 build 1788)

Enjoy

Expand the database. Select the table from the tree view-> Right click and select alter table. You will get the following window shown in the screen shot. Here you can change the charset.