Change Default Titles

there should be a option to change default names of invoices and quotes as in my example in my country invoice with taxes should be named sales tax invoice.

If you choose a tax code from a country where the substitution of Tax Invoice is known to be required, Manager makes that change automatically.

Sales quotes can be renamed when they are entered:

28 PM

Other titles can be changed with custom themes. Read this Guide:

Thanks for Your Guide. it helped me