All my articles were normal site pages. I used the plug-in ‘Post Type Switcher’ to make the pages as posts on a blog. I have just added a new post to my blog and it shows ‘Categories’ as ‘Uncategorised', yet all other posts shows no name. How can I change this so it does not happen again when I add a weekly post?
Did you assign a Category to the new Post when creating it? Can you send a link to the website so I can better understand what you mean by "yet all other posts shows no name". If you do not wish to post it publicly, send it to my Inbox.
The default is uncategorised. Just change it to the right tags or uncheck uncategorised. Tags are a key feature of any blogging platform - you should be using them.