What is the best way to find a 45 single with a search? I’ve tried making singles the highest preference. I’ve tried scans, lookup, lookup browser. I also got the Catalog Number but I don’t see a dropdown search option for it. I see the keyword “CATNO” but I’m having trouble getting it to work. The bottom line is for almost all of my 45’s, Musicbrainz puts the song in the album by itself. What is the best “automated” way to find these singles and save them to my folder structure? It’s very tedious what I’m doing now. I’m tempted to just say it’s not worth it and tale the song in the album and be done with it. Unfortunately I don’t have the MBID for these 45’s I’ve collected. I can try to find it, but that again takes a lot of time. Any suggestions? I wish the slider for preferences worked really well and pulled up the actual singles list for my song title. It should work that way, maybe I’m doing something wrong?
Have you checked on the website to see if the 45s in questions are in the database? It could be your getting the album version, because the single doesn’t exist yet.
This sounds a lot like you are using the scan (AcoustId) button to try to identify sings. Try instead using cluster first, than use the lookup button on the clusters.
As @Billy_Yank suggested, they may not be in the database yet at all , and you may have to add them for Picard to be able to look them up. How to Add a Release - MusicBrainz describes how to add releases, and you can obviously ask questions here on the forum if you have questions about any part of the process. 
The singles are in the database. To me it just seems that Picard doesn’t offer a good way to say that singles are a very high priority. What is the best way to search for a single if I don’t have any of the Musicbrainz ID information?
Could you link to one of the entries in the database that you’re wanting to match to? It sounds to me almost like we have the recordings in the database, but not releases that encapsulate them, and all of Picard’s search functions rely on picking out the latter. If you really wanted, you could add the recording itself manually, but that winds up being a bit clumsier even if you just look at the long-term maintenance.
If I’m just misunderstanding things, and there really are 45 releases already in the database, you actually can weight Picard to choosing them: in the Options window, there’s an arrow to the left of the Metadata option – expand that, select Preferred Releases, and tweak things as you want. I’d recommend selecting the format in the bottom section over (or in addition to) dragging the slider for singles to the right because the format is just a bit more likely to have been specified.
What about my comment above? Do you use the “Scan” button (AcoustID search) or “Lookup”? Do you cluster before using Lookup?
Actually I’ve tried both. Usually cluster first does a better job for albums. For singles I use the AcoustID. Sorry I didn’t respond earlier.
I’m trying to find some documentation on the drop-down on the main screen for album, artist, or track. I’m going to try changing that to track annd see if it does a better job of finding singles.
That dropdown is for the search box at the top, which does a search on MB.org. You can use this to manually load a release into Picard, which is one of the options you have to fix this.
AcoustId scanning for singles should be your second approach after cluster/lookup failed.
I think what I’m looking for is a fast, automated way, of tagging singles. For example, let’s say I load 100 singles with no MBID. It would be great to say, lookup browser “single” after highlighting all 100 singles. Then it tags each single automatically. Yes, I realize that a single can have multiple releases and countries. But my point is to find a way to automate the process of finding a particular type of music, without doing one at a time with Lookup Browser. I’m sure people have better suggestions for how to do this that I do. I’m not surprised if something like this has already been requested. Thanks…For now, it’s probably best to use a software tool like Jaikoz to do what I’m suggesting…Or at least test it to see if it can do this task.
If you don’t care about specific releases etc then a program that has less complexity might be better for you.
If you find something feel free to post what worked for you then maybe future users might be able to benefit from this thread as well 
I just noticed that there appears to be a plug-in for what I need. It’s called “load as non-album track” I’m going to give that a try and report back.
https://community.metabrainz.org/search?q=load%20as%20non%20album%20track%20category%3A13
If I’m careful, and only add my singles for Picard to process, this might work. It’s worth a shot anyway.