At the top of the site while logged in as an admin, do you see a button in the top left that says “My Sites”? If so, from there, hover over that and then hover over Network Admin, then click Plugins. You should see Wordfence installed on the left-hand side now.
If you do not see My Sites, try going to your site URL with the following at the end:
/wp-admin/admin.php?page=WordfenceTools&subpage=diagnostics
There, click Send Report By Email and make sure the email is wftest @ wordfence . com and put your forum username in the second field there and send those. Let me know here when they are sent.
You should be able to manage the login security settings from this page:
/wp-admin/admin.php?page=WFLS#top#settings
There you can disable the captcha completely, or lower the threshold number or 0.2 or 0.3 to reduce the frequency of the verification requirement.
Thanks