Step 1: Go to left-hand side menu, click on "HR Manager" -> Generate letters

Step 2: In "Letter Templates" page please edit "Salaryslip" row (Refer screenshot)

Step 3: You will be able to see editor and in editor  payslip formate is already define.

Step 4: you can add new variables in payslips with reference of below variable define at bottom of editor.

Step 5: If you have knowlege of html code then you can click on "SOURCE" button and edit it.

NOTE: You cant edit salary_details because this strutuce is define in our backend code.