Hi tumateix,
Thank you for your purchase.

The easiest way to do this is via CSS.

If you wish to apply this code to all of your wpDataTables tables, you can put it in “Custom wpDataTables CSS” text area on wpDataTables Settings page,
or if you wish to apply it only on specific pages, you can put it in between style tags in for example html editor bellow tables short codes. E.g.

<style> .wpDataTablesWrapper table.wpDataTable td, .WpDataTablesWrapper table.wpDataTable th
{ text-align: center !important;}
</style>

About the column width:
If you enable Limit table width in table settings you will have option in the column settings to set the column width. ( attachments) 

Best regards.

Hi tumateix,

I can see that you checked Scrollable option and that is why you can not see the Limit table width option.

Only one of the options can be check in the same time, so for the tables that you do not have many columns our suggestion is to uncheck Scrollable option and check Limit table width option.

When the Limit table width option is checked you will have column width filed in the column settings like from my attachments below.

About the code 

Please provide me a temporary WP-admin login for your site where this happens, so we could log in and take a look ‘from the inside’ as that’s the most efficient way to see and resolve the issue. We do not interfere with any data or anything else except for the plugin (in case that’s a production version of the site), and of course we do not provide login data to third party. You can write credentials here just check Private Reply so nobody can see them except us.

Best regards.