JIRA Software system dashboard - totally messed up

[Aaron]

I am using JIRA Software 7.11.0 on demand. After I added an Activity Stream gadget, the nightmare starts:

1. All the top menus are disabled, there is no response and drop-down to click any buttons.
2. I can neither move or remove any gadgets even with administrator account, which give me a message:
   Sorry, you do not have permission to modify this Dashboard. Your dashboard may be out of sync with the server: please reload the page.
   
3. The system keep kicking me out. Every single click just end my sessions. 

Currently, none of my users in the team cannot access their projects since this issue.

Does anyone have any ideas? 

[Nic Brough -Adaptavist-]

I think we need to clarify if you are on Server or Cloud.  You say

" JIRA Software 7.11.0 on demand" which does not make sense.  "On Demand" is the old name for "Cloud", so that suggests you are on Cloud, but there is no version 7.11 for Cloud, it only exists for Server/DC

However, either way, it looks to me like you are trying to edit a dashboard that belongs to someone else.  Even admins cannot do that.

Your third problem about being logged out sounds very odd though, and it also makes me wonder how you are getting to points 1 and 2 if you're always being logged out.  Could you give us a walkthrough of the most simple steps you take to get there (for example:  go to the system base in a browser, enter username and password, click ok, it logs me in and displays my default dashboard, then I click "create" and it takes me to the login page)