Or perhaps the converse, perhaps the data is being auto-restored but there's something wrong with it, and going into app info and clearing cache and data manually will let you start ok with a clean slate?

p.s. the settings on the box are for unpairing, so you can remove your old pairing for cleanliness if you like but it's not required.

says

Close the app and re-start.

Certainly, though, you have to get the app working to make any progress; there’s nothing you can do on the YouView box.

squirted round the offending button, would blow out any dust or other particles that might be affecting the connection.

Do not use anything wet or oily; WD40 might be tempting, but is electrically conductive, so not good to spray into the remote’s crevices.

But if it’s a switch failure, then a new remote will be needed.

I had the Forward Skip on my curvy Humax remote go; air dusting didn’t fix it, so I prised the remote apart and had a look, but the underlying switch had gone. And even if I had found something to fix, the remote wouldn’t go back together properly, even though I’d been careful with it.

I bought a cheap Chinese clone of the remote off Amazon; it did work, but it wasn’t a pleasure to use, so if you do replace the remote, make sure you get a genuine Humax one. 

Doesn’t have to be the original curvy one though, some of the BT and PlusNet ones are better in some respects, albeit worse in others.