Okay: Go Advanced, click on paperclip and browse to a 'snipped' image to upload. (Nice short title: Cortana).
Checked this is showing as a 'Current Attachment' and closed the window.
Now at tutorial step 11:
11. Click/tap on the paperclip icon drop down arrow on the toolbar, and select an uploaded file or image to attach it to the post. (see screenshot below)
I click on the paperclip icon arrow but don't see the name of my attachment. There is a textbox but no text is visible.
However, if I click on the empty box I my image is attached to the post (see below).
NOTE: This is the first time I've tried this and seen the image immediately in the post. Previously I didn't see it until I hit 'Preview', and never saw it in the writing pane.
Previously I was also using the 'Manage Attachments' button rather than the paperclip, based on problems with the paperclip before. Maybe this is a factor but I believed either way should work the same.
So it's possible it's solved for now. I just need to remember to use the paperclip in tenforums and the button in eightforums. Oh, and to never upload more than one attachment into a post here until I've found some virtual lemon juice to squeeze on the invisible writing in that text box
Thanks for the suggestions and for your patience in seeing me through the glitches.