how to change the advertising intervals

Hi,
I am new to BLE firmware and I want to ask a basic question about the firmware of DA14580.
How to change the advertising interval in the DA1458x_SDK_3.0.6.
I`m using the DA1458x_SDK_3.0.6 as the firmware for the DA14580.
First, I use Keil to open the fh_proxr_sdk.uvproj and generate a hex file.
Then, I use the smart snippets to download the generated hex file into the DA14580.
By the power profiler, the advertising interval seems to be 12.5ms.
I want to change the advertising interval to 1s.
So I tried to change the "slave preferred minimum of connention interval" and
"slave preferred maximum of connention interval" to 800,
which were originally set to be 8 and 16 in the sample program of app_proxr_proj.c.
However, the advertising interval hasn't changed.

Original code:
// Peripheral only: *****************************************************************
// Slave preferred Minimum of connection interval
cmd->con_intv_min = 8; // 10ms (8*1.25ms)
// Slave preferred Maximum of connection interval
cmd->con_intv_max = 16; // 20ms (16*1.25ms)
// Slave preferred Connection latency
cmd->con_latency = 0;
// Slave preferred Link supervision timeout
cmd->superv_to = 100;

// Privacy settings bit field
cmd->flags = 0;

Revised code:
// Peripheral only: *****************************************************************
// Slave preferred Minimum of connection interval
cmd->con_intv_min = 800; // 10ms (8*1.25ms)
// Slave preferred Maximum of connection interval
cmd->con_intv_max = 1600; // 20ms (16*1.25ms)
// Slave preferred Connection latency
cmd->con_latency = 0;
// Slave preferred Link supervision timeout
cmd->superv_to = 10000;

Could you tell me the right way to change the advertising interval?

Thanks in advance.
Best regards