TF Securities font size is set in trading software. The steps are as follows:

1. Open Tianfeng independent trading terminal software and enter the trading interface.

2. In the transaction interface, click the "System" option in the menu bar to pop up the drop-down menu.

3. In the drop-down menu, select the "Settings" option to open the settings interface.

4. In the setting interface, select the General tab to set parameters such as font and font size.

5. After the setting is completed, click OK to save the setting.