What do you mean, you got an error? or it simply does nothing?

It did nothing.

I've not had any success changing Read-only on any folder in C: drive,
even the test folder. Followed MS guidelines without success.

I have made a search at Google. These are some of the results.

Is the issue of My Templates folder being Read-only a bit mis-leading?

I haven't yet found a folder on my PC that isn't Read-only but that doesn't stop you putting files into them. To illustrate this, I can save .mbm documents to a folder but not the template.

I still get this error message emailed to self when I try & save templates:
[MLM] Error inserting record from TrackClicktoDB()
1146: Table 'database*****.tbl_mlm_sub_clk_test' doesn't exist

Sounds like database corruption to me, although I used automatic install without a hitch!

I would reinstall but I have just done a maillout & need to see the stats.