The swipe options don’t give such flexibility as you suggest but I have set them to ‘none’ so nothing happens by accident what I did find under ‘threads’ was an option to ‘collapse message when read’ which I’ve switched off in case that’s the culprit!!
Keep us posted if that helps.
I’m not sure which action reported in my previous email has worked but I have had no further problems (to date!). Thanks for your help.