Can anyone help re formatting posts Just recently, despite leaving gap lines in lots of text , the words are published in blocks of almost unreadable text

Also it often takes 3, 4 or 5 attempts to enter the security image (numbers and letters) despite the fact I know they are correct.  ​​​​​​​What am I doing wrong????? 

Absolutely nothing - it is down to "how" you are posting.

If I post a reply in Chrome on my laptop then it is WISIWIG (what I see is what I get)

Post a reply in Chrome on Android (Phone or Tablet) and as you note the text seems to merge to a analogous block.

Golden rule is to make sure appropriate commas and full stops are present so readers get some idea of when to breathe during a sentence OR only reply on a known WISIWIG platform.

As to the "security check" it catches out those of us who choose to consider what we have typed (take time thinking about your post and the system shuffles the code meaning what you saw is no longer what the system is expecting as an entry)

And, as if surprised, having made one post I am prevented from making an immediate subsequent post defined by an indertimate number of seconds.

This type of chat forum must be about 10yrs out of date.

It would also be better if you are responding to a specific comment, to be able to post your answer directly below the comments you are replying to. Many newspaper comments pages like this.. Posting at the end of a comment thread can be difficult to understand the context or who is being replied to - unless it is noted who is being replied to e.g. by # 2 #3 etc 

Reported.