Since the originator of the post has stated that he is not " technically minded", I thought it best to show in pictures what I was trying to explain in the written text. I picked the Fish Tank document as an example as it doesn't contain any sensitive data. You'll also note that in my response in trying to be helpful, I did not make any sarcastic comments!!
I have been away on an extended trip hence the delay in replying. Thanks for the interest you have taken and the suggestions. I have given up on BT Cloud but have detailed the following actions I went through in case it helps anyone else.
I have deleted all items from BT Cloud including those in the deleted folder so that there is nothing at all in BT Cloud. I then went into my laptop and made a copy of an excel file (from a registered copy of Office 2013) and put it in to the BT cloud folder. Tried following the help video from BT but when I opened cloud on my android device I do not get the screen with the + or add sign at the top. Instead I get Photos and videos (I only gave Cloud access to Document) sat the top and the loading circle which seems to stick at that point. There are several other differences on what I see compared to the video. The BT help video also shows that right click on a file gives the option Copy to BT Cloud or Backup. I only get the option to Copy to BT Cloud.
I then uninstalled cloud from my android and installed it again in case I had an old version but it went through the same scenario. I eventually got the excel file in the sync folder but still cannot edit. It still says read only. I tried “save as” to give it a new name and options on where to save came up. The options to save the file were to MS One Drive, This Device (my android), Google drive or Browse to select a Cloud. Saving it to “This Device” option simply saves it in the documents folder on my android device. When taking the Browse option, BT Cloud is not one of the options presumably because I am already in BT Cloud. It gives Snapchat and others that I have never heard of. The default seems to be MS One Drive, however I have disabled that as it is a core part of Win 10 and cannot be uninstalled they tell me, but only disabled from saving files or folders.
I have spent hours trying to get it to work but a 75 years of age I think I can get by without it.