Hi, Jorge.

At the moment the logic for this in the table's Display settings is like this :

If you enable Limit Table Width, the Scrollable slider will be hidden from view. 

The same logic applies in reverse fashion (if Scrollable is enabled, you won’t see Limit Table Width). 

Also, Word Wrap function appears, and can be enabled when Limit Table Width slider is enabled.

Our developers made it like this because they found some issues happen when they tried to allow all the options at the same time.

If you wish to see this improved, please make a development suggestion, and we will do our best.

Please feel free to search on our suggestions page, 

 to see if someone may be already suggested this feature. If you can't see it, feel free to add your suggestion there,  and as more people vote, the feature will move higher on the priority list.

You can certainly follow our changeLog page if you'd like ( it is also available in the plugin dashboard), where we state any changes/new features/bug fixes during updates;

and our newsletter, so you're informed about new features, bug fixes, freebies, etc.

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For the time being, i can only share this custom workaround idea, if you wish to try.

If you wish to use "scrollable" ( for the horizontal scroll)  in the Display options of the table;

while being able to set a custom width for columns.

First enable "scrollable" in the Display tab, 

then you can add this custom CSS to the table's customize / Custom CSS tab :

.wpDataTablesWrapper table.scroll.wpDataTableID-1 {  
  width: max-content !important;  
  table-layout: fixed !important;
}
.wpDataTableID-1 th.column-strap { 
    width:300px !important;
}

You will have to replace the table ID with your table's ID,

and for the column name, you have to set the "origin header name" of the column, after this part : "th.column-"

For example, on my test table here,

if i wish to add the custom width in this CSS for the "firstname" column,

it would be 

.wpDataTableID-2671 th.column-firstname {  
   width:300px !important;
}

Let me know if that helped.

Thank you