MySQL Workbench: how do I set up "ON UPDATE" and CURRENT_TIMESTAMP?

Here is what I do with MySQL Workbench

Data Type: TIMESTAMP Default: CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

I am using MySQL Workbench 5.2.35. Open create/alter table panel, switch to the columns tab, right click on the timestamp field; there you can see possible default and on update options.

Important note: You can use CURRENT_TIMESTAMP as default or updated value for only a single column in a table!

Regarding the UTC question, you can have a look at this question. There is an accepted solution there.

I would suggest you to read MySQL reference manuals as well for Timestamp data type and NOW() function.