How to find and fix entry miss-dated to previous year (in General Ledger)

[doncram]

​Because GnuCash doesn't provide password-locking on past years' data, it's
possible you can accidentally give a past year's date to a new
transaction.​  If that happened, how can you possibly find and fix it?

Under Tools / General Ledger, i can see and edit General Ledger entries
dated in 2017.  I added a few new entries there, accidentally-on-purpose
dated April 1, 2015, and hit enter.  Poof! they disappear upon entry,
cannot be seen.  I know they were accepted, because Reports / Assets &
Liabilities / Balance Sheet reflects the changes to asset and liability
accounts, in report labelled "Balance Sheet 12/31/2017".

Trying to see the expense account changes, I run Reports / Income & Expense
/ Income Statement, but the report labelled "Income Statement For Period
Covering 01/01/2017 to 12/31/2017" doesn't show the 2015 expenses.  (Q1:
how can I see an Income Statement for all time, or for 2015-2017, or for
2015?)

Trying to see the entries in Reports / Assets & Liabilities / General
Journal, I find that works, yay!  I can see the 2015 entries.

Trying to see the entries in Reports / Assets & Liabilities / General
Ledger fails...it states "Transaction Report: / No accounts selected  / This
report requires accounts to be selected in the report options. / Edit
report options".  Clicking on "Edit report options" seems to allow me to
change a start date range for a report named "Transaction Report", but that
has no effect.  Same if I change the report field to "General Ledger".
 (Q2:  how can I get any General Ledger report that I can see?)

I would like to see the entries in a General Ledger editing window and
correct their dates, but I see no way to open such an edit window showing
them.  (Q3: How can a 2015 General Ledger entry be changed?)  Note, I do
see that I could compose reversing entries and enter them for the same 2015
dates, to undo the accidental entries, but it would be far more
straightforward to just correct the General Ledger entries directly, like
can be done for 2017 entries.

Any suggestions will be appreciated! Thanks in advance, Don