I have similar problems with a Tab A and various File Manager apps. It looks to me as if your My Files has got damaged in which case it might be worth reinstalling it. And / or try (yet) another from among the many on Play Store. Two which I can recommend are ES File Manager, very comprehensive and may take a while to master it. Just recently I have been getting good results with Solid Explorer, fairly simple and in particular it has the Two Panel feature along with Drag and Drop (which I am used to in Windows). You display your source folders in the left panel (which can include external drives) and simply drag the file you want to move / copy to the destination panel on the left (again, including external drives). It is reassuring to watch in real time the target file visibly move across to the new destination. I am a novice, especially with Android, but I hope this helps.
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I did not use a secure login on my Sansung Tab A but suddenly It started demanding a series of swipes, all of which it reported as 'incorrect'. After repeated failures I was saved from permanent lock out by an option to use a PIN CODE which works, but I now have to go through many failed swipes first each time I login. I cannot get rid of the unwanted swipes login in Setting. I suspect I have to carry out successful swiping first, but the fact that I cannot do that is why I want to get rid of it in the first place! What can I do, to just have a PIN login or no secured login.
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