I've wathced some of the videos, but they don't help much. I'm not a good follower of instructions that are presented visually. I just want to know how to do the very basic things, like how to tune to a channel. When I power ON the TV, it shows several images at the bottom of the screen: HULU, HDMI3,NETFLIX, VUDO, CBS...Some of these may be leftovers from SLING. (I used to have a subscription to SLING.)
Once I get the basics out of the way, I can probably figure out a lot of the more "advanced" stuff.
BTW, I can get a picture of the TV screen with my phone. Let meknow if that would help.
Assuming you have hooked a Roku Express to your existing TV, the TV should work like it always has. So, after turning on the TV, select whichever input the Roku is attached to and use the Roku remote.
For example, if you attached your Roku to HDMI3 (I'm just guessing that since you mentioned that HDMI3 was on the bottom of your screen) then use your TV remote to select HDMI3. Otherwise, select whichever HDMI port you connected it to.
Confirming what Strega has said, all you need to do, using the TV remote, is to select whatever input the Roku is connected to. The Roku is now feeding the TV and acting like an old fashioned cable box. Next, from the Roku website, create an ID. Turn on the Roku and it will generate an activation code, which you will key into the website. Your Roku box is now linked with your Roku account. A lot of channel icons just got pushed out to the Roku such as Hulu, Sling, Prime Video. You may remove any that you don’t want by highlighting the icon, pressing star (*) and then taking the Remove option,.
You can add any channels that you do want from the Roku box, Home – Streaming Channels and key the name in, or from the web. But you probably can’t view that channel yet as most have a fee. You still have to highlight the icon for that channel, press OK and worry about subscriptions. Most channels have a trial period. A subscription for any channel requires an ID. The channel ID and password can be the same as the Roku ID and password but be aware that they are two separate IDs. Remember them all.