Thanks but how ?

You create new CBTxt language string translations for them.

Do we have to include all sentences in a translation or one sentence by one ?

Question and answer should be translated separately, but you do not need to translate integer based answers. Example as follows.

'What is 1 plus 1?' => 'What is 1 plus 1?',
'Red, banana, apple; which is a color?' => 'Red, banana, apple; which is a color?',
'Red' => 'Red'

What is the different between "duplicate" & "sharing" ?

A duplicate is the same account being logged in at the same time. Sharing is multiple different IP Addresses trying to access the same account (so not necessarily logged in at the same time).

Whatever value I choose for the Captcha background color, noise color and font color it doesn't change. It stays with a white background, blue/grey noise and purple letters.

You don't use letters, please see the description and the existing examples. You need to provide comma separated 3 digit RGB color. For example 255,255,255. Next release will have the description more clear regarding the usage.

Yes, that's exactly what I did, in the config I changed the RGB values, but they have no effect in the captcha.
In the config there's also the possibility to change the font type. That one does work.

Please provide the value you supplied exactly and what parameter.

masterscot wrote: Tried a lot, but for example:
0,0,0
for background color (also tried 1,1,1) : Expected black BG but stays white
150,0,0
for image text color : expected Dark red image letters, but they stay purple
etc.

After every change, saved the config and emptied and refreshed browser (cache).

Was able to confirm. Fixed for next release, sorry about that. BG color won't work at all. The other colors will work as long as they're greater than 0 (e.g. 1,1,1 should work for text color).

For those curious you can monitor progress of next release, its new features, and confirmed bugs below.

forge.joomlapolis.com/projects/cb-cbantispam/issues