Cant Login Due To Authenticity Of Data

I cannot login to a website with FireFox due to "Authenticity Of Data Cannot Be Verified"
Went to Options>Security and unchecked all. Still cant login. Works fine on XP computer.
How do I find whatever is stopping it and allow whatever is needed. No reason to believe this long used site is dangerous. W10 is too "scared" to suit me and my needs. I do not know where Authenticity" is located but would like to reduce standards and allow.

WAIT..I was wrong. Not OS but likely browser settings.It only works the first time after the PW is reset and not after. Failed on Firefox and Google Chrome on the laptop XP it first succeeded on and then neither that nor Desktop XP nor ASUS w10.
You see why foolish as it seems I am against security, privacy, certificates. I can see no good the furnish me but I cannot do my needed work because of it. I was blaming the website at first but now see it the computers and browsers settings. Reporting it does no good. All browsers fail due to this stated reason: authenticity of data cannot be verified.
Can anyone help me here?

 

IE8 on XP laptop works over and over if say NO and YES to secure HTTP connection. Must try several times to be sure. Now retest other XP, 7, and 10 with all browsers. Firefox, Opera, and Chrome are failing on XP laptop.
Must rephrase: I am not against security-in fact I like it, but ONLY security I control, not controlled by others without my OK. I do not know where all these settings are, or even if they are available to ME anyway. But I AM tired of wasting all my spare time trying and failing due to something someone else has set.
Can anyone tell me where this setting is, or if it is even a true reason, or just the only box Microsoft can display and is a lie? Like in my experience are MANY if not MOST boxes.

 

https://support.mozilla.org/en-US/questions/1058856

This worked on one XP PC, the desktop and Mozilla Firefox browser. Seemed to fix FF.
Found it by searching for "authenticity of data cannot be verified". Only one of the 128's changed to false, the dom.vibrator entry. Other 128's and 256's did not change to false when double clicked.
Seems to involve a security ssl3 issue with Firefox anyway.

 

That is what it sounds like BG a FF issue, can you go there with IE successfully?

 

(suddenly my Stay Logged In isnt holding like it used to. I dont even shut down PC and if I come back I am no longer logged in).

Yes - the IE8, IE11, and Microsoft Edge all do work well. The Opera, CHrome, FF do not. All new versions which is no doubt the reason, especially FF. Had to scroll through miles of data to change setting.

IE in Tools> Internet Options> Security> Advanced have the Use ssL2 and ssL3 boxes checked. Dont know where to find this in FF if it is there.

 

Without knowing the site this sounds like a certificate issue. Support for SHA1 certificates has been discontinued for 2016 so this may be an issue. FF and Chrome are at the forefront for this.

 

Also I would disable SSL 2 and SSL 3 in IE. TLS is the preferred protocol. Check all TLS boxes in IE.