Hi there!
When in Edit mode, when I click with Alt + left mouse button on top of an edge, it is selecting a loop edge, avoids two, select one more, etc…
I don’t know what I did; what can I do to revert to the default mode; i.e., selecting only one edge loop?
Yeah, the issue is the topology, if you follow this edge loop, you’ll see she’s making quite a tour all around your mesh.
You’ll have to retopo your model to get what you want.
You might be right; where I used Quad Remesher 1.2 this problem occurs, but not on the other models. What can I do to retopo well enough in order for this not to happen (please, don’t say manual retopology…)?
Sorry, it’s been a while for me since I last retopo with blender, and I don’t quite remember the process, so maybe someone else can help you 
Avoid n-poles, build equal edge counts at the beginning and ends of loops… yeah, long story short, manual topology, sorry
Well with any re-mesher, it is best to always go back in and re-topo to reduce the face count…your chair has 10,098… but…
I believe you can control Quadremesher also by vertex color ( it has been a while so I don’t remember how to use it )…the Original chair should still be in your outliner, as this is a copy unless you deleted it…so you should be able to re-mesh again and change some settings to control the loops and poles…check out this video and around 3.05 he talks about using vertex color to control density ( like in the seat of your chair, does it really need that many faces for an almost flat surface?)
Thank you all for your replies and suggestions. @RSEhlers , I’ll try your method (and you’re right, it doesn’t need that many faces).
