Hi gsfortis,
If each of the three columns has a sub-grid, then I would recommend you choose the tab formatting to be three columns of equal width.

In this way, each sub-grid will have a Search button, click it to search.

In fact, whether the search box appears depends on the screen resolution, browser zoom, and browser width.
For example, I just reduced the browser resolution to 90% and the search box appeared.

Or, I adjusted the browser to the aspect ratio of the phone or tablet, and the search box also appeared.

Finally, I would recommend you try to place all subgrids in a setion, so that the subgrids are all in one column, which is the default layout of the OOTB form.