How do I modify TDS amount and generate e-way bill in BUSY?

If you want to modify TDS amount then open that voucher and change the TDS amount and resave it.
If you want to configure for automatic generation of E-way bill from BUSY, you can follow these steps:
Step 1: First you have to create a GSP (GST Suvidha Provider), you need to visit the eway bill portal and select Webtel Electrosoft Private Limited and Pinnacle Finserv Advisors Private Limited as the GSP Vendor type.
Step 2: Go to Administration and click on configuration.
Step 3: Select Features / Options and click on GST / VAT, here you will see a option called "E-Way Bill Required".
Step 4: Set Y to turn it on and mention your place and pincode and GSP username and password in GSP Configuration tab and save the configuration.
Step 5: Go back to Administration and click on configuration.
Step 6: Choose the Voucher Series Configuration option and select the voucher type for which you want to generate eway bill and e invoice, such as sale, purchase, etc. Then, select the voucher series and click on Voucher Configuration.
Step 7: Here, you will see options of Input Transport Details, Generate "E-Way Bill After Saving" , set Y to enable that. Now your BUSY is ready to generate E-Way Bill Automatically.