How to make the custom tab in forms as default tab instead 'Attachments' tab which is default(OOB)

Always 'Attachments' tab is acting as default tab and not able to keep other tab as default

Hi All,

In our Incident Management module we have couple of tabs in Incident forms along with OOB form 'Attachment'.
When we open new incident, be default the control goes to 'Attachment' though its order is not the first in 'IM.open.Incident' form.
Please can any one help me how to fix this I tried many ways but still 'Attachment' tab is acting as default tab. Instead we need to keep other tabs present on incident form as default tab.

PFA screenshot for reference, ABC tab will be enabled only when the category value is 'install' and it should act as default tab, for rest of the categories this ABC tab will not be available and only 'Attachments' tab is available and the same will act as default tab.

so when the category is given as 'install' this ABC tab will get enable and control should go to this tab instead having the Attachments tab.

Regards,
D_M_K