It appears to me that you’ve updated your iOS and gotten this problem when trying to access QuickBooks Online. This isĀ an on-going issue. I’ll refer you to another Community post, which will provide updates as they become available:

Current status (9/27/2016): Our engineers have resolved this issue – […]

Resolution for 'Community post issue: 'i cannot log in, get message update your browser. My browser is latest version' available: Yes.

The Community post issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the Community post issue yourself by looking for a resolution described in the article. If it is a complex Community post issue or you are unable to solve the issue, you may contact us by clicking here or by using other Community post support options.

For more information about resolving issues related to Community post in Quickbooks/QBO or to get support for the issue 'i cannot log in, get message update your browser. My browser is latest version', click the link below:

Details