It does depend on the remote control you're trying to use. The TV's remote is the one easier to use when you're trying to change channels or change TV inputs to get your Cable/Satellite/Freeview boxes reconnected to the TV set.
Do you have that available? I don't know the model or brand name of your TV or "box"
but ALL remotes do have an Input switching button on them to switch from TV to Input 1, Input 2, Input 3 etc.
We need your TV remote to make it easy to find.
I know I have pictures of remotes here --
This is a Cable or universal remote. Notice the TV and STB buttons at the Top?
Those two buttons make the remote send TV signals or STB (set top box) signals to control your TV or box respectively..
You should press the TV button if you want to control and change the input or channel on your TV set.
Way at the bottom of the remote....notice the A/V input button? That changes the input on the TV set. Aligns it up to the STB box connected to your TV set.
95% of "box" users usually are using that remote control, and the last 5% might use the TV's original remote with the Box's remote.
Let me know if you're using your TV remote, or the box remote. I hope I gave you enough information that you actually FIND that button and understand the TV/STB buttons and what they do.
But if I give you the basics first, then get details later....you may be up and running a lot faster.