By "square screen" I assume you mean STDV. I have one as well, and the recent cable box update 88.1.1 that was pushed out around 16-July-2018 caused a problem for me. I went to Device Settings and it was already set to 480i.
I finally found that setting it to either 1080i or 1080p causes my 480i TV to display correctly. Changing setting back to 480i causes the problem to return.
So I finally left it at 1080. I imagine it'll work until the next update.
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