If with the local signature you mean the user defined one this is a working as designed as the global signature (locked or not) will not prevent the user signature. The global signature is added to the message after the users own signature.

The "Set default" on the gobal signature or template signature lists ( System, Global signatures) can be used to set a default that after setting this can be used in the client options (on user, po or domain ) to set the global signature or template to the option "default global signature" or "global default template" ( in client options, Send, Global signature ) so it is easier to change for all users, po's or domains the one needed

If you would set on user, po or domain a specific global signature and another one is needed you have to change this a few times on the places you set this, the set default on one and use this in the client options overcomes this and a new global signature can be set by setting a new default one for example.

In smaller systems with one global signature defined you can also set the actual signature in client options and change this when needed but in larger environments the set default could be easier

Thanks Rob, I found, that I can manage local user signature with Mailbox Management, is this accessible via REST interface ? 

You can, this is the docu 

https://gwserver:9710/gwadmin-service/static/apidocs/resource_UsersApi.html

Look for "/domains/{domain}/postoffices/{postoffice}/users/{user}/personalsignatures"

The fields needed are mentioned there, i didnt try this one yet but the basic idea is when using the MM user with pw to authenticate

curl -k --user mmuser:novell -X POST -H "Content-Type: application/json" --data "{\"field1\":\"value\",\"field2\":\"value\"}" https://gwserver:9710/gwadmin-service/domains/DOM/postoffices/PO/users/xyz/personalsignatures

This in a quick test adds the simple signature in the MM list for the user

curl -k --user mmuser:novell -X POST -H "Content-Type: application/json" --data "{\"id\":\"\",\"name\":\"Curl\",\"default\":\"false\",\"_default\":\"false\",\"text\":\"test text\",\"html\":\"test html\"}" https://gwmain:9710/gwadmin-service/domains/DOM/postoffices/PO/users/userID/personalsignatures

If I try only disable the signature with

--data "{\"enabled\":\"false\"}"

I'm getting error

{"httpStatusCode":400,"statusCode":56092,"statusMsg":"Must specify signature text, html or both","error":true,"httpStatus":"BAD_REQUEST"}

This is on 24.2, maybe it's fixed with later versions.

Thats not version related, thats just not enough/incorrect use of fields in the data section... and are you using the PUT when changing....

The PUT has these fields

{
  "enabled" : true,
  "add" : "AUTOMATIC",
  "resultInfo" : {
    "nextId" : 12345,
    "outOf" : 12345
  },
  "object" : [ { }, { } ],
  "ids" : "..."
}

Thanks for reply, but I still don't get it. Enable ( disable ) signature is global setting for whole personal signature section. If I want disable signature, it doesn't make sense, that I should set anything inside the section. 

There seems to be more going on.... can you try in gwadmin to enable/disable this as it also does not seem to stick there....

you can change it but after saving and going back in again the setting shows again as it was ....

Im testing a bit more with this...

Yes, same here. The setting dosn't save.

I created a defect for this

I added idea community.opentext.com/.../locking-down-possibility-to-add-personal-signature-when-using-global-signature-templates