I need how to set a password on the wifi AC1200

It looks like Victony has changed it's name to Wavelink:
USER MANUAL WAVLINK AC1200 WL-WN575A3 WL-WN575A2 - YouTube
WN575A3 AERIAL D4 - AC1200 Dual-band Wireless AP/Range Extender/Router - Wavlink

https://www.downloads.netgear.com/files/GDC/EX6110/EX6110_QSG_EN.pdf
Hello, this link you can find all your answers they explein step for step.

Sounds like the connection profile on your device may be corrupted.
The easiest fix for that is make a change to the network names. And verify the passwords and save. And verify the encryption type. Then connect to the new network name and it should ask for the password instead of "Can't Connect". If it fails, take the encryption down a level to WPA2. Some devices still work on that. Other than that do the factory reset back to defaults and setup like when it was new. They always like that.

It is not possible to connect your PC to 5 GHz network. Its wireless card has no capability for 5 GHz band. See this answer for similar question:
Get 5Ghz on laptop

You can buy additional Wi-Fi adapter supporting 802.11a/b/g/n or 802.11ac standard.
Dual band adapter example is here:
WiFi AC Adapter Dongle GMYLE Wireless AC1200 Dual Band 802 11ac USB3 0 866...

Linksys is a good router that will automatically switch based on your devices. They run about $150. Is that out of your range?

I would suggest Linksys - AC1200 Smart Wi-Fi Router

What is it connected to for Internet access? How is it connected?

Power-off & power-on the router, to reset it.
Otherwise, the router is capable of 1 Gigabit (1000 Megabit) throughput, so it should _not_ be the "bottleneck" (unless you are paying your Internet Service Provider for speeds faster than that!!!)

Move closer to your router or try using a wired connection instead of wireless. If you need it to be wireless, then try changing the router to one with a stronger signal (a specification of AC1200 on the router should work well).

connect it with lan cable to your laptop or desktop