This is Ren from the Shopify support team, here to help you out.
While there isn't a way to widen the variant section in that particular spot, what you can do is select all of the variants you're working with and once the boxes and checked, you'll notice a Bulk Editor button:
Clicking this button will take you to a full screen editing page where you won't be required to do as much scrolling right:
The exception to this is if you start adding more field to edit, which in this case you can simply remove ones you aren't currently working on to avoid having to scroll. Let me know if I can clarify any of that for you!
Thanks for reaching out. Can you clarify what you're hoping to do? As far as filters from the steps described above, you can toggle the option to "track quantity" or "continue selling when out of stock" as seen below.
If you wish to alter the product and variant quantities, you can achieve this by clicking on Products > Inventory:
And making the necessary adjustments to the right:
Hope that helps! Please let me know if there is anything I can clarify for you or if you have any additional questions. You can see the full instructions at this link here.
@Ren7 I want to be able to add/remove quantities from the main product main itself, which can only be achieved by scrolling to the right, which cuts off the color/size so it is a very challenging task.
I find it silly to have to go to the inventory page to do that when it can be done on the product itself and is less confusing..